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两个类使用相同的函数创建自定义视图-Swift

extension-methods protocols class swift

Luke · 技术社区 · 6 年前

value 这需要在函数内部传递。我不想在每个类中重复setUpStackView函数的相同代码。我有以下代码:

class Class1: UIStackView {

    var variable1 = "value1"

    override init(frame: CGRect){
      super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder){
      super.init(coder: aDecoder)
    }

    setUpStackView(value: variable1)

}

class Class2: UIStackView {

    var variable2 = "value2"

    override init(frame: CGRect){
      super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder){
      super.init(coder: aDecoder)
    }

    setUpStackView(value: variable2)

}




extension Class1 {

  func setUpStackView(value: String){
    //code to set UIStackView rating control and to use the variable value
  }

}

我如何实现应用程序的扩展 Class2 ? 我被这件事缠住了。任何帮助都将不胜感激!

1 回复 | 直到 6 年前

halfer Jatin Pandey 6 年前

一种解决方案可以将通用代码移动到协议中,您可以从中提取:

protocol  BaseStackView {
    var variable :String { get set }
}

class Class1: UIStackView,BaseStackView {



    var variable = "value1"

    override init(frame: CGRect){
      super.init(frame: frame)
        self.setUpStackView(value: variable)

    }

    required init(coder: NSCoder) {
        super.init(coder: coder)
        self.setUpStackView(value: variable)
    }
}

class Class2: UIStackView,BaseStackView {

    var variable = "value2"

    override init(frame: CGRect){
      super.init(frame: frame)
        self.setUpStackView(value: variable)
    }

    required init(coder: NSCoder) {
        super.init(coder: coder)
        self.setUpStackView(value: variable)
    }



}



extension UIStackView {
    func setUpStackView(value: String) {
        //Your setup here
    }
}

Xavier L. 6 年前

你有很多选择。

class Class2: Class1 {
    var value = "value2" //You have access to Class1's value, so you can change it here
    setUpStackView(value: value) //But there's a problem here
}

但是,不能在类声明的中间调用函数。但您可以在初始值设定项中执行此操作:

class Class2: Class1 {

    override init(frame: CGRect) {
        super.init(frame: frame)
        value = "value2" 
        setUpStackView(value: value) 
    }

    required init(coder aDecoder: NSCoder){
        super.init(coder: aDecoder)
        value = "value2"
        setUpStackView(value: value) 
    }
}

上面的内容有点僵硬,因为您正在引用其自身初始值设定项中的类属性。下面是另一个解决方案:

您可以将设置功能设置为UIStackView的功能扩展:

extension UIStackView {
    func setUpStackView(value: String) { 
        //Your setup here
        self.someProperty = value //self is referring to the stackview itself
    }
}

另一个选项是创建静态函数。

extension Class1 {
    static func setUpStackView(stackVw: UIStackView, value: String) {
        stackVw.someProperty = value 
        //Doing it like this still makes this function "belong" to Class1
        //It also makes it so anyone can set up their stack view like
        //this because they have to pass their stack view in here
    }
}

无论您在哪个类中,也不管您有什么继承层次结构,使用情况都是这样的:

override init(frame: CGRect) {
    super.init(frame: frame)
    Class1.setUpStackVw(stackVw: self, value: self.variable)
}

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    Class1.setUpStackVw(stackVw: self, value: self.variable)
}

还有一个选择是创建一个协议,Class1和Class2都符合该协议。

protocol StackVwWithSpecialSetUp where Self: UIStackView {
    var value: String {get}
}
extension StackVwWithSpecialSetUp {
    func setUpStackView() 
    {
        self.someProperty = self.value
    }
}

然后你会让你的班级遵守它

class Class1Or2: UIStackView, StackVwWithSpecialSetUp {
    var value: String = "blah" //Compiler will force you to implement this
    override init(frame: CGRect) {
        super.init(frame: frame)

        //Now you can use this
        setUpStackVw()
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        //You can use this here too
        setUpStackVw()
    }
}

也许我会这样做,只是不需要 value 财产合计:

class Class1: UIStackView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setUpStackVw()
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setUpStackVw()
    }

    func setUpStackVw()
    {
        self.accessibilityHint = "value1"
    }
}

//////////

class Class2: Class1 {
    override func setUpStackVw()
    {
        self.someProperty = "value2"
    }
}