How to disable pasting in a TextField in Swift?

Question

I\'ve got a TextField with a numberPad and the function runs only if it contains numbers.

The user will crash the app if they paste letters

Answer 1

class CustomUITextField: UITextField {
    override public func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        if action == #selector(cut(_:)) ||
           action == #selector(copy(_:)) ||  
           action == #selector(UIResponderStandardEditActions.paste(_:)) || 
           action == #selector(UIResponderStandardEditActions.select(_:)) || 
           action == #selector(UIResponderStandardEditActions.selectAll(_:)) || 
           action == #selector(UIResponderStandardEditActions.delete(_:)) ||  
           action == #selector(UIResponderStandardEditActions.makeTextWritingDirectionLeftToRight(_:)) ||  
           action == #selector(UIResponderStandardEditActions.makeTextWritingDirectionRightToLeft(_:)) || 
           action == #selector(UIResponderStandardEditActions.toggleBoldface(_:)) || 
           action == #selector(UIResponderStandardEditActions.toggleItalics(_:)) || 
           action == #selector(UIResponderStandardEditActions.toggleUnderline(_:)) || 
           action == #selector(UIResponderStandardEditActions.increaseSize(_:)) || 
           action == #selector(UIResponderStandardEditActions.decreaseSize(_:)) 
        {
             return false
        };
        return true
    }
}

Answer 2

You can just attach an IBAction to your Sent Events (editing changed) of your textfield to filter non numbers out of your string as you type as follow:

@IBAction func changedTextAction(_ sender: UITextField) {
    sender.text = sender.text?.filter(\.isWholeNumber)
}

This will allow the user to paste into the field but it will filter all non digits from the string.