Swift-05-让初始化代码更紧凑

介绍两个特殊的swift风格的初始化方式,可以让初始化代码更紧凑,更清晰

• 1.懒加载,闭包式写法

   fileprivate lazy var closeButton: UIButton = {
       let btn = UIButton()
       btn.setBackgroundImage(UIImage(named: "compose_photo_close"), for: UIControlState.normal)
       btn.isHidden = true
       btn.isUserInteractionEnabled = false
       btn.sizeToFit()
       return btn
   }()
  

• 2.位置参数来初始化

  let mySwitch : UISwitch = {
      view.addSubview($0)
      CenterViewInSuperview($0, horizontal: true, vertical: true)
      $0.addTarget(self, action: "action", forControlEvents: .TouchUpInside)
      return $0
  }(UISwitch())