自定义过渡动画

各视图控制器之间的切换，大概可分为三种

• UITabBarController 他的子视图控制器被选中时，切换子视图
• UINavigationController push/pop一个子视图时
• 一个UIViewController 被presented/dismissed时

自定义非交互式过渡动画

通用部分 1、所要实现自定义过渡动画的ViewController实现对应的delegate，UITabBarViewController对应的是UITabBarControllerDelegate，UINavigationController对应的是UINavigationControllerDelegate。 2、在动画开始时，delegate会调用对应的动画控制器，也就是实现了UIViewControllerAnimatedTransitioning协议的类，这个类可以是任意类型。返回nil，则使用默认动画效果。 3、动画控制器实现对应的方法

• transitionDuration: 动画执行时间
• animateTransition: 实现自定义动画的地方

其他解释在代码注释中 实现一个简单的例子，将UITabBarController的切换视图方式改成左右移动的方式 Swift版本： 只是个简单的例子，所以建立一个 Tabbled Application 模板的项目 实现AppDelegate即可

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?


func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    (self.window!.rootViewController as! UITabBarController).delegate = self
    return true
}
}

extension AppDelegate : UITabBarControllerDelegate{
func tabBarController(tabBarController: UITabBarController, animationControllerForTransitionFromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return self
}}

extension AppDelegate : UIViewControllerAnimatedTransitioning{

//动画的执行时间，需要注意的是一定要和animateTransition:里的动画时间保持一致
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    let vc1 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
    let vc2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    
    let containerView = transitionContext.containerView()!
    
    //这个方法是iOS8之后才有的
    let view1 = transitionContext.viewForKey(UITransitionContextFromViewKey)!
    let view2 = transitionContext.viewForKey(UITransitionContextToViewKey)!
    
    //iOS8之前取得的方式
    //        let view11 = vc1.view
    //        let view22 = vc2.view
    
    
    let r1start = transitionContext.initialFrameForViewController(vc1)
    let r2end = transitionContext.finalFrameForViewController(vc2)
    
    //which key we are going depends on which vc is which the most general way to express this is in terms of index number
    let tab = self.window!.rootViewController as! UITabBarController
    
    let index1 = tab.viewControllers!.indexOf(vc1)
    let index2 = tab.viewControllers!.indexOf(vc2)
    let dir : CGFloat = index1 < index2 ? 1 : -1
    var r1end = r1start
    r1end.origin.x -= r1end.width * dir
    
    var r2start = r2end
    r2start.origin.x += r2start.width * dir
    view2.frame = r2start
    containerView.addSubview(view2)
    
    //避免其他手势事件的干扰
    UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    //执行具体动画，不同效果的代码不同处就是在这了
    UIView.animateWithDuration(0.4, animations: {
        view1.frame = r1end
        view2.frame = r2end
    }) { (_) in
        //防止取消状态
        transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        UIApplication.sharedApplication().endIgnoringInteractionEvents()
    }
}

func animationEnded(transitionCompleted: Bool) {
    if transitionCompleted {
        print("Completed")
    }else{
        print("NO Completed")
    }
}
}

为了让代码显得整洁一些，并且可以是该动画可以在多出更方便的使用，我们将其独立出来。

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?


func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    (self.window!.rootViewController as! UITabBarController).delegate = self
    return true
}

}

extension AppDelegate : UITabBarControllerDelegate{
func tabBarController(tabBarController: UITabBarController, animationControllerForTransitionFromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    let animation = CustomTransitionAimation()
    animation.tab = (self.window!.rootViewController as! UITabBarController)
    return animation
}
}

动画类的实现

import UIKit

class CustomTransitionAimation: NSObject,UIViewControllerAnimatedTransitioning {
var tab : UITabBarController?

//动画的执行时间，需要注意的是一定要和animateTransition:里的动画时间保持一致
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    let vc1 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
    let vc2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    
    let containerView = transitionContext.containerView()!
    
    //这个方法是iOS8之后才有的
    let view1 = transitionContext.viewForKey(UITransitionContextFromViewKey)!
    let view2 = transitionContext.viewForKey(UITransitionContextToViewKey)!
    
    //iOS8之前取得的方式
    //        let view11 = vc1.view
    //        let view22 = vc2.view
    
    let r1start = transitionContext.initialFrameForViewController(vc1)
    let r2end = transitionContext.finalFrameForViewController(vc2)
    
    //which key we are going depends on which vc is which the most general way to express this is in terms of index number
    let tab = self.tab!
    let index1 = tab.viewControllers!.indexOf(vc1)
    let index2 = tab.viewControllers!.indexOf(vc2)
    let dir : CGFloat = index1 < index2 ? 1 : -1
    var r1end = r1start
    r1end.origin.x -= r1end.width * dir
    
    var r2start = r2end
    r2start.origin.x += r2start.width * dir
    view2.frame = r2start
    containerView.addSubview(view2)
    
    //避免其他手势事件的干扰
    UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    //执行具体动画，不同效果的代码不同处就是在这了
    UIView.animateWithDuration(0.4, animations: {
        view1.frame = r1end
        view2.frame = r2end
    }) { (_) in
        //防止取消状态
        transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        UIApplication.sharedApplication().endIgnoringInteractionEvents()
    }
}

func animationEnded(transitionCompleted: Bool) {
    if transitionCompleted {
        print("Completed")
    }else{
        print("NO Completed")
    }
}

}

Objective-C版本

#import "AppDelegate.h"
#import "CusomTransitionAnimation.h"

@interface AppDelegate ()<UITabBarControllerDelegate>

@property(nonatomic,strong) UITabBarController *tabBarController;
@property(nonatomic,strong) CusomTransitionAnimation *customAnimation;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
self.tabBarController = (UITabBarController *)self.window.rootViewController;
self.tabBarController.delegate = self;
return YES;
}

- (id <UIViewControllerAnimatedTransitioning> )tabBarController:(UITabBarController *)tabBarController animationControllerForTransitionFromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
{
CusomTransitionAnimation *animation = [[CusomTransitionAnimation alloc]init];
animation.tabBarController = self.tabBarController;
return  animation;
}

- (CusomTransitionAnimation *)customAnimation
{
if (!_customAnimation) {
    _customAnimation = [[CusomTransitionAnimation alloc]init];
    _customAnimation.tabBarController = self.tabBarController;
}
return _customAnimation;
}

@end

动画类

//.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface CusomTransitionAnimation : NSObject<UIViewControllerAnimatedTransitioning>

@property(nonatomic,strong) UITabBarController *tabBarController;

@end

//.m
#import "CusomTransitionAnimation.h"

@implementation CusomTransitionAnimation

- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext
{
return 0.4;
}
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
UIView *containerView = [transitionContext containerView];

UIViewController *vc1 = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *vc2 = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

UIView *view1 = [transitionContext viewForKey:UITransitionContextFromViewKey];
UIView *view2 = [transitionContext viewForKey:UITransitionContextToViewKey];

CGRect vc1start = [transitionContext initialFrameForViewController:vc1];
CGRect vc2end = [transitionContext finalFrameForViewController:vc2];

NSUInteger index1 = [self.tabBarController.viewControllers indexOfObject:vc1];
NSUInteger index2 = [self.tabBarController.viewControllers indexOfObject:vc2];

int dir = index1 < index2 ? 1 : -1;

CGRect vc1end = vc1start;
vc1end.origin.x -= vc1end.size.width * dir;

CGRect vc2start = vc2end;
vc2start.origin.x += vc2start.size.width * dir;
view2.frame = vc2start;
[containerView addSubview:view2];

[[UIApplication sharedApplication]beginIgnoringInteractionEvents];
[UIView animateWithDuration:0.4 animations:^{
    view1.frame = vc1end;
    view2.frame = vc2end;
} completion:^(BOOL finished) {
    [transitionContext completeTransition:(!transitionContext.transitionWasCancelled)];
    [[UIApplication sharedApplication]endIgnoringInteractionEvents];
}];
}

- (void)animationEnded:(BOOL)transitionCompleted
{
if (transitionCompleted) {
    NSLog(@"Completed");
}else{
    NSLog(@"No Completed");
}
}
@end

UINavigationController实现是类似的，只不过调用动画类的方式不同

viewController实现

import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.navigationController!.delegate = self
}

@IBAction func pushAction(sender: AnyObject) {
    let second = SecondViewController()
    self.navigationController!.pushViewController(second, animated: true)
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
}

extension ViewController : UINavigationControllerDelegate{
func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    //operation 用来区分是push还是pop操作
    if operation == .Push {
        return CustomPushTransitionAimation()
    }
    else if operation == .Pop{
        return CustomPopTransitionAimation()
    }
    return nil
}
}

Push动画

import UIKit

class CustomPushTransitionAimation: NSObject,UIViewControllerAnimatedTransitioning {

//动画的执行时间，需要注意的是一定要和animateTransition:里的动画时间保持一致
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
//        let vc1 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
//        let vc2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    
    let containerView = transitionContext.containerView()!
    
    //这个方法是iOS8之后才有的
    let view1 = transitionContext.viewForKey(UITransitionContextFromViewKey)!
    let view2 = transitionContext.viewForKey(UITransitionContextToViewKey)!
    
    //iOS8之前取得的方式
    //        let view11 = vc1.view
    //        let view22 = vc2.view

    view2.transform = CGAffineTransformMakeScale(0.1, 0.1)
    containerView.addSubview(view2)
    
    //避免其他手势事件的干扰
    UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    //执行具体动画，不同效果的代码不同处就是在这了
    UIView.animateWithDuration(0.4, animations: {
        view2.transform = CGAffineTransformIdentity
    }) { (_) in
        //防止取消状态
        transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        UIApplication.sharedApplication().endIgnoringInteractionEvents()
    }
}

func animationEnded(transitionCompleted: Bool) {
    if transitionCompleted {
        print("Completed")
    }else{
        print("NO Completed")
    }
}

}

Pop动画

import UIKit

class CustomPushTransitionAimation: NSObject,UIViewControllerAnimatedTransitioning {

//动画的执行时间，需要注意的是一定要和animateTransition:里的动画时间保持一致
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
//        let vc1 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
//        let vc2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    
    let containerView = transitionContext.containerView()!
    
    //这个方法是iOS8之后才有的
    let view1 = transitionContext.viewForKey(UITransitionContextFromViewKey)!
    let view2 = transitionContext.viewForKey(UITransitionContextToViewKey)!
    
    //iOS8之前取得的方式
    //        let view11 = vc1.view
    //        let view22 = vc2.view

    view2.transform = CGAffineTransformMakeScale(0.1, 0.1)
    containerView.addSubview(view2)
    
    //避免其他手势事件的干扰
    UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    //执行具体动画，不同效果的代码不同处就是在这了
    UIView.animateWithDuration(0.4, animations: {
        view2.transform = CGAffineTransformIdentity
    }) { (_) in
        //防止取消状态
        transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        UIApplication.sharedApplication().endIgnoringInteractionEvents()
    }
}

func animationEnded(transitionCompleted: Bool) {
    if transitionCompleted {
        print("Completed")
    }else{
        print("NO Completed")
    }
}
}

可交互的自定义过渡动画

有两种实现方式

使用百分比驱动

使用这种方式比较简单，还是按照上述的方法先实现不可交互的自定义动画。接下来实现回调方法

func tabBarController(tabBarController: UITabBarController, interactionControllerForAnimationController animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?

主要是UIPercentDrivenInteractiveTransition的使用，实质是frozen animation。

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

var rightEdgr : UIScreenEdgePanGestureRecognizer!
var leftEdgr : UIScreenEdgePanGestureRecognizer!
var inter : UIPercentDrivenInteractiveTransition!//这个类是关键
var interacting = false

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    let tab = (self.window!.rootViewController as! UITabBarController)
    tab.delegate = self
    
    let sep = UIScreenEdgePanGestureRecognizer(target: self, action: #selector(pan))
    sep.edges = .Right
    sep.delegate = self
    tab.view.addGestureRecognizer(sep)
    self.rightEdgr = sep
    
    let sep2 = UIScreenEdgePanGestureRecognizer(target: self, action: #selector(pan))
    sep2.edges = .Left
    sep2.delegate = self
    tab.view.addGestureRecognizer(sep2)
    self.leftEdgr = sep2
    
    return true
}

}

extension AppDelegate : UITabBarControllerDelegate{
func tabBarController(tabBarController: UITabBarController, animationControllerForTransitionFromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
//        let animation = CustomTransitionAimation()
//        animation.tab = (self.window!.rootViewController as! UITabBarController)
//        return animation
    return self
}

func tabBarController(tabBarController: UITabBarController, interactionControllerForAnimationController animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
    if self.interacting {
        return self.inter
    }
 return nil
}
}

extension AppDelegate : UIGestureRecognizerDelegate{

func gestureRecognizerShouldBegin(gestureRecognizer: UIGestureRecognizer) -> Bool {
    let tab = self.window!.rootViewController as! UITabBarController
    var result = false
    
    if gestureRecognizer == self.rightEdgr {
        result = (tab.selectedIndex < tab.viewControllers!.count - 1)
    }
    else{
        result = tab.selectedIndex > 0
    }
    return result
}

func pan(g : UIScreenEdgePanGestureRecognizer) -> Void {
    //重点需要处理的地方
    let v = g.view!
    let tab = self.window!.rootViewController as! UITabBarController
    let delta = g.translationInView(v)
    let percent = fabs(delta.x/v.bounds.width)
    switch g.state {
    case .Began:
        self.inter = UIPercentDrivenInteractiveTransition()
        self.interacting = true
        if g == self.rightEdgr {
            tab.selectedIndex = tab.selectedIndex + 1
        }else{
            tab.selectedIndex = tab.selectedIndex - 1
        }
        print("selectedIndex = \(tab.selectedIndex)")
    case .Changed:
        self.inter.updateInteractiveTransition(percent)
    case .Ended:
        if percent > 0.5 {
            self.inter.finishInteractiveTransition()//调用该方法，将快速结束之前所设置的操作
        }else{
            self.inter.cancelInteractiveTransition()//调用该方法，将恢复原状
        }
        self.interacting = false
    case .Cancelled:
        self.inter.cancelInteractiveTransition()
        self.interacting = false
    default : break
    }
    
}
}



extension AppDelegate : UIViewControllerAnimatedTransitioning{

//动画的执行时间，需要注意的是一定要和animateTransition:里的动画时间保持一致
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    let vc1 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
    let vc2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    
    let containerView = transitionContext.containerView()!
    
    //这个方法是iOS8之后才有的
    let view1 = transitionContext.viewForKey(UITransitionContextFromViewKey)!
    let view2 = transitionContext.viewForKey(UITransitionContextToViewKey)!
    
    //iOS8之前取得的方式
    //        let view11 = vc1.view
    //        let view22 = vc2.view
    
    
    let r1start = transitionContext.initialFrameForViewController(vc1)
    let r2end = transitionContext.finalFrameForViewController(vc2)
    
    //which key we are going depends on which vc is which the most general way to express this is in terms of index number
    let tab = self.window!.rootViewController as! UITabBarController
    
    let index1 = tab.viewControllers!.indexOf(vc1)
    let index2 = tab.viewControllers!.indexOf(vc2)
    let dir : CGFloat = index1 < index2 ? 1 : -1
    var r1end = r1start
    r1end.origin.x -= r1end.width * dir
    
    var r2start = r2end
    r2start.origin.x += r2start.width * dir
    view2.frame = r2start
    containerView.addSubview(view2)
    /*
    //避免其他手势事件的干扰
    UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    //执行具体动画，不同效果的代码不同处就是在这了
    UIView.animateWithDuration(0.4, animations: {
        view1.frame = r1end
        view2.frame = r2end
    }) { (_) in
        //防止取消状态
        transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        UIApplication.sharedApplication().endIgnoringInteractionEvents()
    }
 */
    
    let opts : UIViewAnimationOptions = self.interacting ? .CurveLinear : []
    if !self.interacting {
        UIApplication.sharedApplication().beginIgnoringInteractionEvents()
    }
    UIView.animateWithDuration(0.4, delay: 0, options: opts, animations: {
        view1.frame = r1end
        view2.frame = r2end
        }) { (_) in
            let canceld = transitionContext.transitionWasCancelled()
            transitionContext.completeTransition(!canceld)
            if UIApplication.sharedApplication().isIgnoringInteractionEvents(){
                UIApplication.sharedApplication().endIgnoringInteractionEvents()
            }
    }
}

func animationEnded(transitionCompleted: Bool) {
    if transitionCompleted {
        print("Completed")
    }else{
        print("NO Completed")
    }
    
    let tab = self.window!.rootViewController as! UITabBarController
    print(tab.selectedIndex)
    
    }
}

不使用百分比驱动

这种写法虽然看起来会稍微复杂一些，但是他的可定制程度更高，因为我们可以直接对fromView 和 toView等进行直接操作。

不在需要具体实现animateTransition方法，但是他还是要存在的，因为他的协议必须实现的方法。

func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    
}

将其中的代码放到实现了协议UIViewControllerInteractiveTransitioning的类中实现。放到方法

func startInteractiveTransition(transitionContext: UIViewControllerContextTransitioning){
}

中就可以了。

这次使用OC实现，都熟悉下：

#import "AppDelegate.h"

@interface AppDelegate ()<UIViewControllerAnimatedTransitioning,UIViewControllerInteractiveTransitioning,UITabBarControllerDelegate,UIGestureRecognizerDelegate>

@property(nonatomic,strong) id<UIViewControllerContextTransitioning>transitionContext;
@property(nonatomic,strong) UIScreenEdgePanGestureRecognizer *leftEdgr;
@property(nonatomic,strong) UIScreenEdgePanGestureRecognizer *rightEdgr;
@property(nonatomic,assign) BOOL interacting;
@property(nonatomic,assign) CGRect r1end;
@property(nonatomic,assign) CGRect r2start;

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.

UITabBarController *tab = (UITabBarController *)self.window.rootViewController;
tab.delegate = self;
self.leftEdgr = ({
    UIScreenEdgePanGestureRecognizer *pan = [[UIScreenEdgePanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
    pan.edges = UIRectEdgeLeft;
    pan.delegate = self;
    [tab.view addGestureRecognizer:pan];
    pan;
});
self.rightEdgr = ({
    UIScreenEdgePanGestureRecognizer *pan = [[UIScreenEdgePanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
    pan.edges = UIRectEdgeRight;
    pan.delegate = self;
    [tab.view addGestureRecognizer:pan];
    pan;
});

self.r1end = CGRectZero;
self.r2start = CGRectZero;

return YES;
}

#pragma mark - Actions

- (void)pan:(UIScreenEdgePanGestureRecognizer *)ges
{
UIView *gesView = ges.view;
UITabBarController *tab = (UITabBarController *)self.window.rootViewController;
CGPoint delta = [ges translationInView:gesView];
CGFloat percent = delta.x/gesView.bounds.size.width;

UIViewController *fromVC,*toVC;
UIView *fromView,*toView;
CGRect fromRectStart,toRectEnd;

if (self.transitionContext) {
    fromVC = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    toVC = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    fromView = [self.transitionContext viewForKey:UITransitionContextFromViewKey];
    toView = [self.transitionContext viewForKey:UITransitionContextToViewKey];
    
    fromRectStart = [self.transitionContext initialFrameForViewController:fromVC];
    toRectEnd = [self.transitionContext finalFrameForViewController:toVC];
}

switch (ges.state) {
    case UIGestureRecognizerStateBegan: {
        self.interacting = YES;
        if (ges == self.leftEdgr) {
            tab.selectedIndex = tab.selectedIndex - 1;
        }else{
            tab.selectedIndex = tab.selectedIndex + 1;
        }
        break;
    }
    case UIGestureRecognizerStateChanged:{
        //可以在这里对fromView 和 toView 进行直接操作，所以，可定制程度高
        
        fromRectStart.origin.x += (self.r1end.origin.x - fromRectStart.origin.x) * percent;
        fromView.frame = fromRectStart;
        NSLog(@"fromRect : %@",NSStringFromCGRect(fromRectStart));
        CGRect toRectStart = self.r2start;
        toRectStart.origin.x += (toRectStart.origin.x - self.r2start.origin.x) * percent;
        toView.frame = toRectStart;
        NSLog(@"toRect : %@",NSStringFromCGRect(toRectStart));
        //在UITabBarController的切换中可能看不出来这句话有什么用处，但是在UINavigationController中这个就很有用了，可以自己处理NavigationBar的效果等。
        [self.transitionContext updateInteractiveTransition:percent];
        break;
    }
    case UIGestureRecognizerStateEnded: {
        if (percent > 0.5) {
            //达到要求，设置成最终状态
            [UIView animateWithDuration:0.2 animations:^{
                fromView.frame = self.r1end;
                toView.frame = toRectEnd;
            } completion:^(BOOL finished) {
                [self.transitionContext finishInteractiveTransition];
                [self.transitionContext completeTransition:YES];
            }];
        }
        else{
            //恢复原状
            [UIView animateWithDuration:0.2 animations:^{
                fromView.frame = fromRectStart;
                toView.frame = self.r2start;
            } completion:^(BOOL finished) {
                [self.transitionContext cancelInteractiveTransition];
                [self.transitionContext completeTransition:NO];
            }];
        }
        
        self.interacting = NO;
        self.transitionContext = nil;
        
        break;
    }
    case UIGestureRecognizerStateCancelled: {
        
        //恢复原状
        fromView.frame = fromRectStart;
        toView.frame = self.r2start;
        
        [self.transitionContext finishInteractiveTransition];
        [self.transitionContext completeTransition:NO];
        
        self.interacting = NO;
        self.transitionContext = nil;
        
        break;
    }
        default:
        break;
}}

#pragma mark - UIGestureRecognizerDelegate

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
UITabBarController *tab = (UITabBarController *)self.window.rootViewController;
BOOL result = NO;

if (gestureRecognizer == self.leftEdgr) {
    result = tab.selectedIndex > 0;
}else{
    result = tab.selectedIndex < tab.viewControllers.count - 1;
}

return result;
}

#pragma mark - UITabBarControllerDelegate

- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
                           interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController
{
return self.interacting ? self : nil;
}

- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
                 animationControllerForTransitionFromViewController:(UIViewController *)fromVC
                                                   toViewController:(UIViewController *)toVC
{
return self.interacting ? self : nil;
}

#pragma mark - UIViewControllerAnimatedTransitioning

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
return 0.4;
}

//这个要实现，但是要保持为空
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{

}

#pragma mark - UIViewControllerInteractiveTransitioning
//这个其实就是要实现 animateTransition: 原来实现的功能
- (void)startInteractiveTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{

self.transitionContext = transitionContext;

//即最终要达到的状态
UIView *containerView = [transitionContext containerView];

UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

//    UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];

CGRect fromRectStart = [transitionContext initialFrameForViewController:fromVC];
CGRect toRectEnd = [transitionContext finalFrameForViewController:toVC];

UITabBarController *tab = (UITabBarController *)self.window.rootViewController;
NSUInteger fromIndex = [tab.viewControllers indexOfObject:fromVC];
NSUInteger toIndex = [tab.viewControllers indexOfObject:toVC];
int dir = fromIndex < toIndex ? 1 : -1;

CGRect fromRectEnd = fromRectStart;
fromRectEnd.origin.x -= fromRectEnd.size.width * dir;

CGRect toRectStart = toRectEnd;
toRectStart.origin.x += toRectStart.size.width * dir;
toView.frame = toRectStart;
[containerView addSubview:toView];

self.r1end = fromRectEnd;
self.r2start = toRectStart;
}

@end

自定义Presented ViewController的过渡动画

实现主要要两种方式

• 不使用presentation controller
• 使用presentation controller

不使用presentation controller

需要注意的地方是

• 协议transitioningDelegate声明的位置
• 区分present 和 dismiss
• 只有当modalPresentationStyle *不是 .FullScreen *的时候，才能使用如下方式判定是present还是dismiss

上代码

import UIKit

class ViewController2: UIViewController {

override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
    //这个不能再 viewDidLoad 里执行，太晚了
    self.transitioningDelegate = self
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    self.transitioningDelegate = self
}
override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    self.view.backgroundColor = UIColor.blueColor()
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    self.presentingViewController!.dismissViewControllerAnimated(true, completion:
    nil)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
}

extension ViewController2 : UIViewControllerTransitioningDelegate{
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return self
}

func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return self
}
}

extension ViewController2 : UIViewControllerAnimatedTransitioning{
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 0.4
}

func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    
    let containerView = transitionContext.containerView()!
    
    //For a presentation that is not .FullScreen,the unused view is nil.
    let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)
    let toView = transitionContext.viewForKey(UITransitionContextToViewKey)
    
    //distinguish the cases
    //dismiss
    if fromView != nil {
        UIView.animateWithDuration(0.4, animations: { 
            fromView!.transform = CGAffineTransformMakeScale(0.1, 0.1)
            fromView!.alpha = 0
            }, completion: { (_) in
                transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        })
    }
        //presenting
    else if toView != nil{
        let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
        let toRectEnd = transitionContext.finalFrameForViewController(toVC)
        toView!.frame = CGRectInset(toRectEnd, 40, 40)
        toView!.transform = CGAffineTransformMakeScale(0.1, 0.1)
        toView!.alpha = 0
        containerView.addSubview(toView!)
        //also can modify the containerView
//            containerView.backgroundColor = UIColor.greenColor()
        UIView.animateWithDuration(0.4, animations: {
            toView!.transform = CGAffineTransformIdentity
            toView!.alpha = 1.0
        }) { (_) in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        }
    }
}
}

在.FullScreen 类型的presented中，会取得presenting View，并将其添加到containerView中，其他类型的则是，containerView是在presenting view之前的，不能给containerView添加动画，并且containerView不会移除。

使用Presentation Controller

在此之前，需要理解的一些东西

• Animation Controller 用来负责动画效果，也就是presented View 如何移动到最终目标位置
• Presentation Controller 确定presented View的最终位置，还有向containerView上添加一些视图，例如半透明效果什么的。 举个例子来说明，如果只是实现了UIPresentationController 而没有做上面的那些工作，会使用默认动画弹出。

接下来说说实现： 在实现上面效果的基础上，需要在做几点工作

• 在设置presented viewController的 transitioningDelegate属性的同时，还需要设置其的modalPresentationStyle为.Custom，这个是必须的。（注意代码位置）

     // NB if we want to modify the _animation_, we need to set the transitioningDelegate
    self.transitioningDelegate = self
    // if we want to modify the _presentation_, we need to set the style to custom
    // customize presentation only on iPhone
    // how will we find out which it is? we have no traitCollection yet...
    // I know, let's ask the window
    if UIApplication.sharedApplication().keyWindow!.traitCollection.userInterfaceIdiom == .Phone {
        self.modalPresentationStyle = .Custom
    }
  

• 在实现另一个方法

  @available(iOS 8.0, *)
  optional public func presentationControllerForPresentedViewController(presented: UIViewController, presentingViewController presenting: UIViewController, sourceViewController source: UIViewController) -> UIPresentationController?
  

接下来便是在 UIPresentationController的子类中重载他的方法来达到我们所要的效果

方法的说明：

// Position of the presented view in the container view by the end of the presentation transition.
// (Default: container view bounds)
public func frameOfPresentedViewInContainerView() -> CGRect

返回presented view的最终位置

使用下面的方法来给containerView添加或移除一些额外的视图

presentationTransitionWillBegin
presentationTransitionDidEnd
dismissalTransitionWillBegin
dismissalTransitionDidEnd

使用下面方法来个添加的额外视图进行布局

containerViewWillLayoutSubviews
containerViewDidLayoutSubviews

方法

shouldPresentInFullscreen

默认返回的是true，如果返回false，会将presentation改变为 .CurrentContext

主要就这几个，完结。

Transition Coordinator的使用

主要注意几个方法的使用就可以了

• animateAlongsideTransition:completion: 可以用来给已经在视图上的子视图添加动画效果

  - (void)viewWillAppear:(BOOL)animated
  {
  [super viewWillAppear:animated];
  if (self.transitionCoordinator != nil) {
    [self.transitionCoordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        NSLog(@"Transition Animation");
        
        self.animationView.center = self.view.center;
        
    } completion:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        NSLog(@"Transition completion");
    }];
  }
  else{
    NSLog(@"Transition is NULL");
  }
  }
  

• notifyWhenInteractionEndsUsingBlock:

监控视图返回时手势动作是否成功。比如在UINavigationController中左侧滑动返回时，需要在上一个ViewController中实现。

- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
if (self.transitionCoordinator != nil) {
    
    [self.transitionCoordinator notifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        if ([context isCancelled]) {
            NSLog(@"1 Interaction Cancelled");
            return ;
        }
        NSLog(@"1 Interaction Ends");
    }];
}
else{
    NSLog(@"1 Transition is NULL");
}
}