Iphone – How to assign a unique key to a UITouch throughout it’s lifecycle

Figured I would post the snippet right here instead:

Make sure you declare support for the UITextViewDelegate protocol.

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    if([text isEqualToString:@"\n"]) {
        [textView resignFirstResponder];
        return NO;
    }

    return YES;
}

Swift 4.0 update:

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if text == "\n" {
        textView.resignFirstResponder()
        return false
    }
    return true
}

[canvasView.hiddenTextView becomeFirstResponder];

will probably do what you want.

The responder chain on the iPhone is a slightly tricky thing. I find it's usually easier to avoid overlapping controls, so that at any given instance it's completely unambiguous as to which control should receive input from which touches.

If you're overlapping a lot of controls, and often switching between which ones are hidden or visible, that's a good sign that you might want to just implement more subclasses of UIViewController, and switch between those instead of swapping in out and the controls. Another option is to make custom subclasses of UIView and swap those in and out instead -- by which I mean, actually remove the old one from the subview (not hiding it), and adding the new one.

Of course, there are some times when hiding/showing is just a lot easier than subclassing.

I hope that helps. Reference: Apple's UIResponder docs. (Note that any UIViewController or UIView is a subclass of UIResponder.)