Swift 开发之懒加载的实例详解

/// A display link that keeps calling the `updateFrame` method on every screen refresh. private lazy var displayLink: CADisplayLink = {   self.isDisplayLinkInitialized = true   let displayLink = CADisplayLink(target: TargetProxy(target: self), selector: #selector(TargetProxy.onScreenUpdate))   displayLink.add(to: .main, forMode: self.runLoopMode)   displayLink.isPaused = true   return displayLink }() 

public var priority: Float {     get {       return internalTask.priority     }     set {       internalTask.priority = newValue     }   } 

/*  用到时再加载  多次使用只加载一次  */ lazy var names :[String] = {   let names = ["why", "lmj", "swd"]   print("------") 按理说应该只打印一次   return names }()  //方式一：仅仅创建button lazy var btn1:UIButton = UIButton()  //方式二:可以设置更多btn的属性 lazy var btn :UIButton = {   let btn = UIButton()   btn.setTitle("按钮", for: .normal)   btn.setImage(UIImage(named:""), for: .normal)   return btn }() 

//MARK: 点击事件 func buttonClick(_ sender:UIButton) {    print("----/(names.count)") } 

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