Question

我知道必须调用超类的指定初始值设定项，我认为init(type: UIButtonType)已经调用了一个指定的初始化程序，所以我在子类的方便初始化程序中使用它，但是失败了

class TSContourButton: UIButton {
enum ContourButtonSizeType {
    case large
    case small
}

convenience init(type:ContourButtonSizeType) {
    self.init(type: .custom)
}

然后，我尝试了这个。它编译好了。但是，它看起来并不专业

class TSClass: UIButton {

convenience init(frame: CGRect, myString: String) {
    self.init(frame: frame)
    self.init(type: .custom)
}

所以，我怀疑我可能认为错了。所以，我做了一些测试。它成功地调用了super convenience initializer。为什么我不能在self.init(type: .custom)

的子类的便捷初始值设定项中使用UIButton

class person: UIButton {
var name: String = "test"

override init(frame: CGRect) {
    super.init(frame: .zero)
    self.name = "one"
}

convenience init(myName: String) {
    self.init(frame: .zero)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

}

class man: person {
convenience init(mySex: Int) { // it successfully call superclass convenience initializer
    self.init(myName: "info")
}

Answer 1

例如，如果name是您的必填字段，则在函数中实现所有初始设置。如果name不可用，您应该处理。如果没有提供类型，我会将small作为默认选项。

// MARK:- Designated Initializers
required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    initialSetup(type: .small)
}

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

    initialSetup(type: .small)
}

// MARK:- Convenience Initializers
convenience init(type: ContourButtonSizeType) {
    self.init(frame: .zero)

    initialSetup(type: type)
}

func initialSetup(type: ContourButtonSizeType) {
    // handle all initial setup 
}

Answer 2

init(type: UIButtonType)不是UIButton的指定初始值设定项，init(frame: CGRect)不是UIButton的指定初始值设定项

您只需要覆盖init(frame: CGRect)

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let button1 = MyButton(type: .custom)
    }

}

class MyButton: UIButton {

    // 初始化父类的指定构造器，然后你就可以获得父类的便利构造器
    // overwrite the designated initializer of the super class, then you can automatically inherit the convenience initializer of the super class
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

如果要自定义按钮，可以添加convenience init(myType: UIButton.ButtonType)

    class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let button1 = MyButton(type: .custom)
        let button2 = MyButton(myType: .custom)
    }

}


class MyButton: UIButton {

    // 初始化父类的指定构造器，然后你就可以获得父类的便利构造器
    // overwrite the designated initializer of the super class, then you can automatically inherit the convenience initializer of the super class
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    // 创建自己的遍历构造器
    // this is what you want
    convenience init(myType: UIButton.ButtonType) {
        self.init(type: myType) // called the convenience initializer which you automatically inherit from super class
        // customize your own button
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

如果这对您有用，可以给我点赞（づ￣ 3￣）づ

为什么我不能在UIButton的子类的便捷初始化器中使用“self.init（type：.custom）”

2 个答案: