基于MVVM构建聊天App （二）登录UI的实现

1、一个完整的开发流程

一般的，一个正常的流程包括：

产品定需求，给出原型图
团队确认需求
由设计师开始设计图，同步开发做开发前的准备工作，如技术调查，前后端如何配合等
设计师完成设计后，团队对比设计图和原型图再次确认需求，在团队确认需求后设计师会把设计图发布到蓝湖或者zeplin上
开发团队开始开发工作
开发完成后由开发者自测一般我们在开发中编写的单元测试代码也属于自测
开发者自测后由产品测试，事实上在开发过程中，产品也应该实时的关注开发
交由专业测试人员做测试
发布内测版本，做大规模测试
提交App Store审核

2、storyboard启动流程

一般的如果新建了一个Objective-C工程，默认先调用main函数，main函数内部会调用UIApplicationMain函数。

int main(int argc, char * argv[]) {
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

但在Swift项目中，并没有main.m文件也没有main函数。Swift工程是在AppDelegate中用一个@UIApplicationMain标签。那么UIApplicationMain做了哪些操作呢：

创建UIApplication单例对象
创建UIApplication的委托对象，即AppDelegate
开启事件循环监听系统事件，当坚挺到对应的系统事件时会通知AppDelegate
创建最底层的UIWindows对象，
读取Info.plist中设置的默认启动storyboard文件名称
加载设置的is Initial View Controllerstoryboard文件，同时创建对应的View Controller对象
设置创建的View Controller为UIWindows的根视图rootViewController
显示Windows上的试图

运行工程可以看到如下图：最底层是一个UIWindwos

windows

3、没有storyboard启动App

一般的一个工程，默认从main.storyboard中的设置的Initial view controller启动的，那么我们该如何设置自己的初始启动View Controller呢？

在前面我们工程的结构：RPChat_iOS是UI的显示以及交互相关的代码，所以在RPChat_iOS新建文件夹SignIn

SignIn

新建登陆界面Controller命名为SignInViewController

在AppDelegatedidFinishLaunchingWithOptions launchOptions回调方法中添加代码,设置SignInViewController为默认启动控制器：

if #available(iOS 13, *) {
    
} else {
     window = UIWindow.init()
     window?.frame = UIScreen.main.bounds
     window?.makeKeyAndVisible()
     let signInVC = SignInViewController()
     window?.rootViewController = signInVC
}

在SceneDelegateoptions connectionOptions方法中添加代码：

guard let windowScene = (scene as? UIWindowScene) else { return }

window = UIWindow(frame: windowScene.coordinateSpace.bounds)
window?.windowScene = windowScene
window?.backgroundColor = .white
let tabBar = SignInViewController()
window?.rootViewController = tabBar
window?.makeKeyAndVisible()

4、登录UI的实现

先看一下这是最终效果图：

light Mode

1、Auto Layout

至于UI，考虑到版本兼容和后期维护我采用了系统NSLayoutAnchor适配，

NSLayoutAnchor常用属性

leadingAnchor
trailingAnchor
leftAnchor
rightAnchor
topAnchor
bottomAnchor
widthAnchor
heightAnchor
centerXAnchor
centerYAnchor
firstBaselineAnchor
lastBaselineAnchor

关于Auto Layout其他更多使用细节请参考官方文档:

High Performance Auto Layout

Apple Develope NSLayoutConstraint

Apple Develope NSLayoutAnchor

WWDC 2018 What's New in Cocoa Touch

2、UI实现

新建一个View命名SignInRootView作为登录界面的主View，采用懒加载的方式初始化视图

最顶部的Logo图片实现代码：

lazy var logoImg: UIImageView = {
        self.addSubview($0)
        $0.translatesAutoresizingMaskIntoConstraints = false
        let top = $0.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 44)
        let centerX = $0.centerXAnchor.constraint(equalTo: self.centerXAnchor, constant: 0)
        let width = $0.widthAnchor.constraint(equalToConstant: 120)
        let height = $0.heightAnchor.constraint(equalToConstant: 120)
        NSLayoutConstraint.activate([top, centerX, width, height])
        return $0
    }(UIImageView())

用户名输入框实现代码：

 lazy var accountNumberView: UIView = {
        self.addSubview($0)
        $0.translatesAutoresizingMaskIntoConstraints = false
        let top = $0.topAnchor.constraint(equalTo: logoImg.bottomAnchor, constant: 20)
        let left = $0.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 40)
        let right = $0.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -40)
        let height = $0.heightAnchor.constraint(equalToConstant: 50)
        NSLayoutConstraint.activate([top, left, right, height])
        $0.layer.cornerRadius = 25
        return $0
    }(UIView())
 
    
    lazy var accountNumberLab: UITextField = {
        accountNumberView.addSubview($0)
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.topAnchor.constraint(equalTo: accountNumberView.topAnchor, constant: 0).isActive = true
        $0.leftAnchor.constraint(equalTo: accountNumberView.leftAnchor, constant: 16).isActive = true
        $0.rightAnchor.constraint(equalTo: accountNumberView.rightAnchor, constant: -16).isActive = true
        $0.bottomAnchor.constraint(equalTo: accountNumberView.bottomAnchor, constant: 0).isActive = true
        $0.font = UIFont.init(name: "PingFangTC-Semibold", size: 19)
        return $0
    }(UITextField())

密码输入框实现代码：

lazy var inputPasswordView: UIView = {
           self.addSubview($0)
           $0.translatesAutoresizingMaskIntoConstraints = false
           let top = $0.topAnchor.constraint(equalTo: accountNumberView.bottomAnchor, constant: 20)
           let left = $0.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 40)
           let right = $0.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -40)
           let height = $0.heightAnchor.constraint(equalToConstant: 50)
           NSLayoutConstraint.activate([top, left, right, height])
           $0.layer.cornerRadius = 25
           return $0
       }(UIView())
    
       
    lazy var inputPasswordTxt: UITextField = {
           inputPasswordView.addSubview($0)
           $0.translatesAutoresizingMaskIntoConstraints = false
           $0.topAnchor.constraint(equalTo: inputPasswordView.topAnchor, constant: 0).isActive = true
           $0.leftAnchor.constraint(equalTo: inputPasswordView.leftAnchor, constant: 16).isActive = true
           $0.rightAnchor.constraint(equalTo: inputPasswordView.rightAnchor, constant: -16).isActive = true
           $0.bottomAnchor.constraint(equalTo: inputPasswordView.bottomAnchor, constant: 0).isActive = true
           $0.font = UIFont.init(name: "PingFangTC-Semibold", size: 19)
           return $0
       }(UITextField())

登录按钮实现代码：

lazy var signInBtn: UIButton = {
        self.addSubview($0)
        $0.translatesAutoresizingMaskIntoConstraints = false
        let top = $0.topAnchor.constraint(equalTo: inputPasswordView.bottomAnchor, constant: 20)
        let left = $0.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 40)
        let right = $0.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -40)
        let height = $0.heightAnchor.constraint(equalToConstant: 50)
        NSLayoutConstraint.activate([top, left, right, height])
        $0.layer.cornerRadius = 25
        $0.titleLabel?.font = UIFont.init(name: "PingFangTC-Semibold", size: 20)
        $0.setTitle(NSLocalizedString("Sign In", comment: ""), for: .normal)
        return $0
   }(UIButton())

此处代码较多，具体实现请看代码： gitub RPChat

3、设置背景颜色

由于设计师给出的颜色一般为16进制，此处需要做一个转码处理：

public class func hexStringToColor(_ hexadecimal: String) -> UIColor {
        var cstr = hexadecimal.trimmingCharacters(in:  CharacterSet.whitespacesAndNewlines).uppercased() as NSString;
        if(cstr.length < 6){
            return UIColor.clear;
        }
        if(cstr.hasPrefix("0X")){
            cstr = cstr.substring(from: 2) as NSString
        }
        if(cstr.hasPrefix("#")){
            cstr = cstr.substring(from: 1) as NSString
        }
        if(cstr.length != 6){
            return UIColor.clear;
        }
        var range = NSRange.init()
        range.location = 0
        range.length = 2
        let rStr = cstr.substring(with: range);
        range.location = 2;
        let gStr = cstr.substring(with: range)
        range.location = 4;
        let bStr = cstr.substring(with: range)
        var r :UInt32 = 0x0;
        var g :UInt32 = 0x0;
        var b :UInt32 = 0x0;
        Scanner.init(string: rStr).scanHexInt32(&r);
        Scanner.init(string: gStr).scanHexInt32(&g);
        Scanner.init(string: bStr).scanHexInt32(&b);
        return UIColor.init(red: CGFloat(r)/255.0, green: CGFloat(g)/255.0, blue: CGFloat(b)/255.0, alpha: 1)
    }

然后就可以用设计师给的16进制设置背景颜色：

signInBtn.backgroundColor = UIColor.hexStringToColor("0xF5BE62")

4、Drak Mode适配

(1)、文本和UIView背景颜色适配

由于iOS 13之后苹果处理Drak Mode,作为开发者也应该做相应的兼容处理。现在我在代码中并没有做兼容处理，此时调整模拟器为暗模式，运行工程可以看到在暗模式下，用户名和密码输入框背景色不见了。此时就应该做暗模式的兼容处理。

drak mode

此处我的做法也很简单，对UIColor做extension处理，然后再扩展方法中分别对Drak Mode和Light Mode两种模式做对应的处理，代码如下：

extension UIColor {
   /// 当前是否是暗模式
    public class var drakMode: Bool {
        if #available(iOS 13.0, *) {
            let currentMode = UITraitCollection.current.userInterfaceStyle
            if currentMode == .dark {
                return true
            }
        }
        return false
    }
    public class func isDrakMode() -> Bool {
        if #available(iOS 13.0, *) {
            let currentMode = UITraitCollection.current.userInterfaceStyle
            if currentMode == .dark {
                return true
            }
        }
        return false
    }
    
    /// UIView背景颜色
    public class var darkModeViewColor: UIColor {
        if #available(iOS 13.0, *) {
            return .systemBackground
        } else {
            return .white
        }
    }
    public class func configDarkModeViewColor() -> UIColor {
        if #available(iOS 13.0, *) {
            return .systemBackground
        } else {
            return .white
        }
    }
    /// 文字颜色
    public class var darkModeTextColor: UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return .white
                } else {
                    return .black
                }
            }
        } else {
            return .black
        }
    }
    public class func configDarkModeTxtColor() -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return .white
                } else {
                    return .black
                }
            }
        } else {
            return .black
        }
    }
    /// 子UIView背景颜色
    public class var subDarkModeViewColor: UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return UIColor(red: 100/255, green: 100/255, blue: 100/255, alpha: 1)
                } else {
                    return .groupTableViewBackground
                }
            }
        } else {
            return .groupTableViewBackground
        }
    }
    public class func configSubDarkModeViewColor() -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return UIColor(red: 100/255, green: 100/255, blue: 100/255, alpha: 1)
                } else {
                    return .groupTableViewBackground
                }
            }
        } else {
            return .groupTableViewBackground
        }
    }
    /// 设置默认带颜色的view背景
    public class func configDarkModeViewWith(_ dfaultColor: UIColor) -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return UIColor(red: 100/255, green: 100/255, blue: 100/255, alpha: 1)
                } else {
                    return dfaultColor
                }
            }
        } else {
            return dfaultColor
        }
    }
    /// 设置带默认颜色的文字颜色
    public class func configDarkModeTxtColorWith(_ dfaultColor: UIColor) -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return .systemBackground
                } else {
                    return dfaultColor
                }
            }
        } else {
            return dfaultColor
        }
    }
    /// 设置Placeholder文字颜色
    public class var placeholderColor: UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return UIColor(red: 255, green: 255, blue: 255, alpha: 0.25)
                } else {
                    return UIColor(red: 0, green: 0, blue: 0, alpha: 0.25)
                }
            }
        } else {
            return UIColor(red: 0, green: 0, blue: 0, alpha: 0.25)
        }
    }
    public class func configPlaceholderColor() -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor{(trainCollection) -> UIColor in
                if trainCollection.userInterfaceStyle == .dark {
                    return UIColor(red: 255, green: 255, blue: 255, alpha: 0.25)
                } else {
                    return UIColor(red: 0, green: 0, blue: 0, alpha: 0.25)
                }
            }
        } else {
            return UIColor(red: 0, green: 0, blue: 0, alpha: 0.25)
        }
    }
}

只需要在设置颜色时通过方法或者属性设置即可：

accountNumberView.backgroundColor = .subDarkModeViewColor
inputPasswordView.backgroundColor = .subDarkModeViewColor

accountNumberView.backgroundColor = UIColor.configSubDarkModeViewColor()
inputPasswordView.backgroundColor = UIColor.configSubDarkModeViewColor()

从结果上来说，这两种方式没有任何区别。一般用属性的话在设置或计算时看起来更自然一些，例如我用 a = 0会比a = getData() 看起来更直观自然一些。《Clearn Code》一书中强调，对方法或函数的命名尽量使用动词或动词短语，所以在使用一个方法时，通常的代码表示要做一些事情。此处我只是修改UIView的背景颜色，所以我个人觉得使用属性设置更直观一些。

(2)、图片DrakMode适配

在Xcode中修改图片为Any,Dark，Xcode会自动生成一组新的暗模式下的填充图片，把图片拖入即可。

图片适配

(3)、监听traitCollection的变化

在一些特殊的地方需要根据当前系统是否处于暗模式分别作出处理，如一般情况下隐私协议用WKWebView加载,在正常情况下为白色背景黑色文字，在暗模式下为黑色背景白色文字，此时上面的代码已经不能满足我的需求了。此时就需要对当前系统是否是暗模式做监听处理。

我的做法是定一个DrakModeProtocol协议，在需要监听的Controller中，遵循这个协议即可。

/// 协议
public protocol DrakModeProtocol : NSObjectProtocol {
    @available(iOS 13.0, *)
    var traitCollection: UITraitCollection { get }

    
    @available(iOS 13.0, *)
    func traitCollectionDidChange(_ traitCollection: UITraitCollection?)
}

/// 使用方法
extension MineWKWebViewController: DrakModeProtocol {
    override func traitCollectionDidChange(_ traitCollection: UITraitCollection?) {
           if #available(iOS 13.0, *) {
               if UITraitCollection.current.userInterfaceStyle == .dark {
                   webView.evaluateJavaScript("document.body.style.backgroundColor=\"#000000\"") { (data, error) in
                       
                   }
                   webView.evaluateJavaScript("document.body.style.webkitTextFillColor=\"#FFFFFF\"") { (data, error) in
                       
                   }
               } else {
                   webView.evaluateJavaScript("document.body.style.backgroundColor=\"#FFFFFF\"") { (data, error) in
                       
                   }
                   webView.evaluateJavaScript("document.body.style.webkitTextFillColor=\"#000000\"") { (data, error) in
                       
                   }
               }
           }
       }
}

隐私协议

再次运行项目，可以看到界面已经兼容了暗模式：

drak Mode

本文主要写了：

不通过storyboard启动App
登录UI的实现
Drak Mode的适配

本文demo: Github RPChat