在子类和UIViewController中使用UITextViewDelegate

Question

我对UITextView进行了子类化，并在像textViewDidChangeSelection这样的子类中实现了一些委托方法，但我还需要在视图控制器中为UITextView委托获取通知。因此，如果我创建了子类的对象并在视图控制器中设置了textview委托，那么委托方法只会在视图控制器中被通知，而不会在子类中被通知。我需要通知两个班级。我使用的语言是swift 2

我尝试在子类委托中继承UITextViewDelegate：

@objc protocol CustomTextViewDelegate:UITextViewDelegate {

    func customTextViewDidChangeSize(chatTextView: CustomTextView)

}

然后在VC中：

let customTV = CustomTextView()
customTV.customTextViewDelegate = self

但是任何文本视图委托方法都不会被调用。

Answer 1

问得好。这是一个不太好的答案，因为它需要你重写所有的委托方法，因此在iOS版本中不稳定，以防委托方法随着时间的推移而改变。

在这种方法中，ViewController和CustomTextField都可以访问委托事件。

class CustomTextView: UITextView {
   override var delegate: UITextViewDelegate? {
      set {
         superDelegate = newValue
      } get {
         return superDelegate
      }
    }

    private weak var superDelegate: UITextViewDelegate?

    init() {
       super.init(frame: .zero, textContainer: nil)
       super.delegate = self
    }

    func textDidChange(text: String?) {
        // do something
    }

}

extension BoundTextView: UITextViewDelegate {
    public func textViewDidChange(_ textView: UITextView) {
        // catch text-change events here
        textDidChange(text: String?) 
        superDelegate?.textViewDidChange?(textView)
    }

    public func textViewDidEndEditing(_ textView: UITextView) {
        superDelegate?.textViewDidEndEditing?(textView)
    }

    public func textViewDidChangeSelection(_ textView: UITextView) {
        superDelegate?.textViewDidChange?(textView)
    }

    public func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
       return superDelegate?.textViewShouldBeginEditing?(textView) ?? false
    }

    public func textViewDidBeginEditing(_ textView: UITextView) {
        superDelegate?.textViewDidBeginEditing?(textView)
    }

    public func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
       return superDelegate?.textViewShouldEndEditing?(textView) ?? false
    }

    public func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        return superDelegate?.textView?(textView, shouldChangeTextIn: range, replacementText: text) ?? false
    }

    public func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
        return superDelegate?.textView?(textView, shouldInteractWith: URL, in: characterRange, interaction: interaction) ?? false
    }

    public func textView(_ textView: UITextView, shouldInteractWith textAttachment: NSTextAttachment, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
        return superDelegate?.textView?(textView, shouldInteractWith: textAttachment, in: characterRange, interaction: interaction) ?? false
    }
}

我们覆盖delegate并将对它的引用存储在一个单独的变量(称为superDelegate)中。CustomTextField将自身分配给super.delegate并实现UITextView-delegate。我们必须确保每个委托事件都会触发相应的superDelegate事件。

我们的“ViewController”现在可以将自己指定为CustomTextView的委托：

class ViewController: UIViewController {

   ...
   lazy var textField: CustomTextView {
      let textView = CustomTextField()
      textView.delegate = self 
      return textField
   }()
   ...


}

extension ViewController: UITextViewDelegate {

   // implement only the delegate-methods you need

}

现在，ViewController和CustomTextField都可以访问UITextFieldDelegate。

Answer 2

不能同时将两个对象委托给UITextView对象。因此，您应该为CustomTextView创建新的协议(CustomTextViewDelegate)，并在其中创建委托属性。让你的ViewController确认这个CustomTextViewDelegate并实现它的方法。在CustomTextView的UITextViewDelegate方法实现中，可以调用适当的CustomTextViewDelegate方法。

Answer 3

@nayooti的方法很好，但是我必须做一些修复才能正常工作，主要的一个是一些委托方法不会被调用(例如shouldChangeTextIn range和textViewDidChange )。

我发现可以通过在被覆盖的delegate变量的get访问器上返回super.delegate而不是superDelegate来修复它。

class CustomTextView: UITextView {
    
    override var delegate: UITextViewDelegate? {
        set {
            superDelegate = newValue
        } get {
            return super.delegate
        }
    }
    
    private weak var superDelegate: UITextViewDelegate?
    
    init() {
        super.init(frame: .zero, textContainer: nil)
        super.delegate = self
    }
    
    override public init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        super.delegate = self
    }
    
    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        super.delegate = self
    }
    
    func textDidChange(text: String?) {
        // Do something
    }
    
}

extension CustomTextView: UITextViewDelegate {
    
    public func textViewDidChange(_ textView: UITextView) {
        // Catch text-change events here
        textDidChange(text: textView.text)
        superDelegate?.textViewDidChange?(textView)
    }
    
    public func textViewDidEndEditing(_ textView: UITextView) {
        superDelegate?.textViewDidEndEditing?(textView)
    }
    
    public func textViewDidChangeSelection(_ textView: UITextView) {
        superDelegate?.textViewDidChange?(textView)
    }
    
    public func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
        return superDelegate?.textViewShouldBeginEditing?(textView) ?? true
    }
    
    public func textViewDidBeginEditing(_ textView: UITextView) {
        superDelegate?.textViewDidBeginEditing?(textView)
    }
    
    public func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
        return superDelegate?.textViewShouldEndEditing?(textView) ?? true
    }
    
    public func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        return superDelegate?.textView?(textView, shouldChangeTextIn: range, replacementText: text) ?? true
    }
    
    public func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
        return superDelegate?.textView?(textView, shouldInteractWith: URL, in: characterRange, interaction: interaction) ?? true
    }
    
    public func textView(_ textView: UITextView, shouldInteractWith textAttachment: NSTextAttachment, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
        return superDelegate?.textView?(textView, shouldInteractWith: textAttachment, in: characterRange, interaction: interaction) ?? true
    }
    
}