Swift /代码重构/如何将参数添加到UIView

Question

我有以下UIView扩展来添加背景。

extension UIView { 
func addBackground() { 
    // screen width and height: 
    let width = UIScreen.mainScreen().bounds.size.width 
    let height = UIScreen.mainScreen().bounds.size.height 

    let imageViewBackground = UIImageView(frame: CGRectMake(0, 0, width, height)) 
    imageViewBackground.image = UIImage(named: "index_clear") 
    imageViewBackground.clipsToBounds = true 

    // you can change the content mode: 
    imageViewBackground.contentMode = UIViewContentMode.ScaleAspectFill 
    self.addSubview(imageViewBackground) 
    self.sendSubviewToBack(imageViewBackground) 
}} 

我

self.view.addBackground() 

什么使通用的扩展的最佳实践打电话了吗？我想改变这样的画面：

self.view.addBackground("index_clear") 

或

self.view.addBackground("other_background_image") 

帮助是非常赞赏。

Answer 1

试试这个：

extension UIView { 
func addBackground(imgName : String) { 
    // screen width and height: 
    let width = UIScreen.mainScreen().bounds.size.width 
    let height = UIScreen.mainScreen().bounds.size.height 

    let imageViewBackground = UIImageView(frame: CGRectMake(0, 0, width, height)) 
    imageViewBackground.image = UIImage(named: imgName) 
    imageViewBackground.clipsToBounds = true 

    // you can change the content mode: 
    imageViewBackground.contentMode = UIViewContentMode.ScaleAspectFill 
    self.addSubview(imageViewBackground) 
    self.sendSubviewToBack(imageViewBackground) 
}} 

Answer 2

如果你想避免破坏你的代码中的任何现有的实现，你可以使用默认参数的方法，做这样的事情：

extension UIView { 
    func addBackground(imageName: String = "index_clear") { 
     // screen width and height: 
     let width = UIScreen.mainScreen().bounds.size.width 
     let height = UIScreen.mainScreen().bounds.size.height 

     let imageViewBackground = UIImageView(frame: CGRectMake(0, 0, width, height)) 
     imageViewBackground.image = UIImage(named: imageName) 
     imageViewBackground.clipsToBounds = true 

     // you can change the content mode: 
     imageViewBackground.contentMode = UIViewContentMode.ScaleAspectFill 
     self.addSubview(imageViewBackground) 
     self.sendSubviewToBack(imageViewBackground) 
    } 
} 


// You can continue to use it like so 
myView.addBackground() // uses index_clear 

// or 
myView.addBackground("index_not_clear") // uses index_not_clear