Swift 如何初始化UIButton子类？

我试图在Swift中为UIButton的子类添加一个双值 尝试了所有类型的初始化、获取和设置选项，但我无法让它工作

所以我从这个开始

class CVSTButton : UIButton {
    var cvstPosition: Double

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

        super.init(coder: aDecoder)
    }
}

然后我试着：

class CVSTButton : UIButton {
    var cvstPosition: Double {
        get {
            return self.cvstPosition
        }
        set {
            self.cvstPosition = newValue
        }

    }

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

---

我不明白这里有什么不对。。。。请帮助…

在调用

super.init（）

之前，需要在声明或

init

中使用初始值。（2） 对

fatalError

的调用被放入，这样您就不会忘记实现初始值设定项——这基本上是故意的崩溃。删除

在声明中设置初始值，无需

init

：

class CVSTButton : UIButton {
    var cvstPosition: Double = 0
}

或在初始值设定项中设置初始值：

class CVSTButton : UIButton {
    var cvstPosition: Double

    required init(coder aDecoder: NSCoder) {
        cvstPosition = 0

        super.init(coder: aDecoder)
    }
}

Swift>=2.2： 只需从UIButton继承，您的子类就变成了type

.Custom

default

Swift 2： 斯威夫特：

---

使用Swift 3，您可以根据需要从以下七个代码片段中选择一个来解决问题

---

1.使用自定义初始值设定项创建

UIButton

子类 此解决方案允许您使用属性的适当值创建

UIButton

子类的实例。使用此解决方案，您只能以编程方式创建UIButton子类的实例

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    convenience init(squareOf value: Int) {
        self.init(value: value * value)
    }

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    override init(frame: CGRect) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(frame: frame)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

用法：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(value: 0)
        // let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(squareOf: 10)
        // let button = CustomButton(value: 100) // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 100
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(frame: .zero)
        //let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button: CustomButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        print(button.myValue) // prints 0
    }

}

---

2.使用方便的初始值设定项创建

UIButton

子类 此解决方案允许您使用属性的适当值创建

UIButton

子类的实例。使用此解决方案，您只能以编程方式创建

UIButton

子类的实例

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    convenience init(squareOf value: Int) {
        self.init(value: value * value)
    }

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    override init(frame: CGRect) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(frame: frame)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

用法：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(value: 0)
        // let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(squareOf: 10)
        // let button = CustomButton(value: 100) // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 100
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(frame: .zero)
        //let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button: CustomButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        print(button.myValue) // prints 0
    }

}

---

3.使用

init（frame:CGRect）

initializer创建

UIButton

子类 使用此解决方案，您只能以编程方式创建

UIButton

子类的实例

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    convenience init(squareOf value: Int) {
        self.init(value: value * value)
    }

    required init(value: Int = 0) {
        // set myValue before super.init is called
        self.myValue = value

        super.init(frame: .zero)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    override init(frame: CGRect) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(frame: frame)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

}

用法：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(value: 0)
        // let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(squareOf: 10)
        // let button = CustomButton(value: 100) // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 100
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(frame: .zero)
        //let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button: CustomButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        print(button.myValue) // prints 0
    }

}

---

4.使用

init？（coder-aDecoder:NSCoder）

初始值设定项创建

UIButton

子类 使用此解决方案，您可以从故事板创建

UIButton

子类的实例

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    required init?(coder aDecoder: NSCoder) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(coder: aDecoder)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    override init(frame: CGRect) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(frame: frame)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

    required init?(coder aDecoder: NSCoder) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(coder: aDecoder)

        // set other operations after super.init if required
        backgroundColor = .red
    }

}

用法：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(value: 0)
        // let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(squareOf: 10)
        // let button = CustomButton(value: 100) // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 100
    }

}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(frame: .zero)
        //let button = CustomButton() // also works
        button.setTitle("Hello", for: .normal)

        // auto layout
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

        print(button.myValue) // prints 0
    }

}

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button: CustomButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        print(button.myValue) // prints 0
    }

}

---

5.使用

init（frame:CGRect）

和

init？（coder-aDecoder:NSCoder）

初始化器创建

UIButton

子类 使用此解决方案，您可以通过编程或从故事板创建

UIButton

子类的实例

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    required init?(coder aDecoder: NSCoder) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(coder: aDecoder)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

}

import UIKit

class CustomButton: UIButton {

    var myValue: Int

    override init(frame: CGRect) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(frame: frame)

        // set other operations after super.init, if required
        backgroundColor = .red
    }

    required init?(coder aDecoder: NSCoder) {
        // set myValue before super.init is called
        self.myValue = 0

        super.init(coder: aDecoder)

        // set other operations after super.init if required
        backgroundColor = .red
    }

}

---

6.使用属性的默认属性值创建

ui按钮

子类 作为先前解决方案的替代方案，可以在初始值设定项之外为属性指定初始值

import UIKit

class CustomButton: UIButton {

    var myValue: Int = 0

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

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

        // set other operations after super.init if required
        backgroundColor = .red
    }

}

---

7.使用具有可选类型的属性创建

UIButton

子类 如果在创建按钮时不想/无法为属性设置默认值，则必须将属性类型设置为可选

import UIKit

class CustomButton: UIButton {

    var myValue: Int? = nil

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

        // set other operations after super.init, if required
        backgroundColor = .red
    }

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

        // set other operations after super.init if required
        backgroundColor = .red
    }

}

---

注意：我在XCode 8.3.3中使用Swift 3

当我需要向

ui按钮添加自定义属性和方法时，这是一个简单易行的解决方法：

class CVSTButton: UIButton {

    var cvstPosition: Double

    static func button(withCVSTPosition cvstPosition: Double) -> CVSTButton {

        let button = CVSTButton(type: .detailDisclosure) // You may adjust the initializer used to suit your needs.

        button.cvstPosition = cvstPosition // Then you can simply set the the properties (which are passed as arguments to the factor/class method)

        return button

    }

}

要使用它：

let cvstButton = CVSTButton.button(withCVSTPosition: 2.0)

太好了，所以我只需要声明并给变量一个init值！在Swift 2.2中，在
init
之后需要一个问号，因此
required init？（coder-aDecoder:NSCoder）{
您希望在其中插入“public”。例如：覆盖public类funcNot，当然。请阅读public是项目之间的作用域。我喜欢您给出了为什么要使用每个代码段的场景。惊人的响应-希望有更多这样的问题得到回答。如何调用便利init（）如果按钮是一个出口？在代码片段3的使用部分，框架被用作初始值设定器，使用类似于
CustomButton（框架：CGRect（x:100，y:300，宽度：200，高度：50））
的东西会更清楚，而不是
CustomButton（框架：.zero）
和自动布局