UITextView paste method override

I really want to be able to detect a paste event in a UITextView, however it appears this cannot be done.

I originally tried subclassing a UITextView and overriding the p开发者_JAVA百科aste: method, but it never gets called on a paste event.

Has anyone been able to do this? A previous question on the same ilk didn't have an answer back in August...

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The text view doesn't catch the paste: event because it wasn't the actual responder is not the text view, but the private web view (UIWebDocumentView) that powers the text view.

However, on paste, the web view will call the text view's (private) -[UITextView keyboardInput:shouldInsertText:isMarkedText:], and in turn, the text view's delegate's -textView:shouldChangeTextInRange:replacementText:.

Therefore, you just need to implement -textView:shouldChangeTextInRange:replacementText: in the text view's delegate.

(Of course, normal keyboard input will trigger this method too. There's no perfect way to distinguish them.)

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@KennyTM what I did for one of my applications was keep up with the current text length and the previous text length. If the (currentTextLength - previousTextLength) was greater than 1, then the user must have pasted something

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With iOS 14 you have to do this in two parts to avoid showing the user notification that you are checking the UIPasteboard. In my case I did not want to do anything bad with the user data but I did want to do some special formating when the user did paste into the UITextView.

Step 1: Create a custom UITextView and override paste()

import UIKit

protocol TouchableTextViewDelegate : class{
    func touchesDidBegin()
    func pasting()
}

class TouchableTextView: UITextView {
    weak var touchableDelegate : TouchableTextViewDelegate?

    
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        if self.isFirstResponder{
            return true
        }
        touchableDelegate?.touchesDidBegin()
        return false
    }
    
    override func paste(_ sender: Any?) {
        touchableDelegate?.pasting()
        super.paste(sender)
    }
    
}

Step 2: In the file location where you handle the shouldChangeTextIn create a variable and be sure to set the delegate for the TouchableTextView. In my case

//top of the view
var isPasting : Bool = false

//also when creating UITextView use both delegates
textView.touchableDelegate = self
//add the normal delegate
textView.delegate = self

extension SliderTextView : TouchableTextViewDelegate{
    func pasting() {
        self.isPaste = true
    }
    
    func touchesDidBegin() {
        sliderEditingDelegate?.touchesDidBegin(sliderTextView: self)
    }
}

Step 3: Inside shouldChangeTextIn I handle the action like this

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
     let isPaste = self.isPaste
     //be sure to set this to false
     self.isPaste = false
     if isPaste,
        let pt = UIPasteboard.general.string,
        text.contains(pt){ 
        //you will see the paste notification and that is good for the user
        // but only when the user pastes
        // do whatever special thing or formatting you want to do

      }   
      return true
}

The good is that you will not trigger the notification unless the user is pasting in the UITextView.

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To detect if a user is parsing a text in a textView, compare the replacementText in the shouldChangeTextInRange delegate with the text the user is currently holding in the UIPasteboard. Then take action depending on requirements.

for code, see my answer in the following question:

how to know when text is pasted into UITextView