How to trigger textViewdelegate on programmatical UITextView edits - ios

Question

If I am typing with the keyboard, then textViewDidChange and shouldChangeTextInRange are always called. But when I change the textView programmatically, the delegate methods aren't called. How do I get a programmatic change in textView to trigger delegate methods?
Update
Is there some other way for simulating keyboard input programmatically?

Answer 1

I solve this issue in my code using the insert method instead to change the value of the text string.
textView.insertText("Your Text")

Answer 2

Just ran into this question a few years later but had a hard time finding other good answers, so I want to demonstrate Satheesh's technique answered here with greater detail that worked for me for future readers and people that experience a similar issue.
Technique
First, add an observer to the textView:
let property = "text" //can also be attributedText for attributed strings
self.textView.addObserver(self, forKeyPath: property, options: NSKeyValueObservingOptions(rawValue: 0), context: nil)
Next, override the observeValue function:
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if object as? NSObject == self.textView {
//your code here
}
}
The observeValue function will run after the property value of the textView you added the observer to has been changed. Note that when you programmatically set the text of the textView like:
textView.text = "programmatically assigned text"
The shouldChangeTextIn delegate function is ran before the observer is called. As a side note, if you are using attributedText as the property, I would also recommend setting the property in that function and returning false:
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
let newString = NSString(string: textView.text!).replacingCharacters(in: range, with: text)
textView.attributedText = createAttributedString(text: newString)
return false
}
This ensures that you do not duplicate the text you are inputting into the text and attributedText properties. You can also use the delegate function to reject input, such as new lines, and it will not call the observeValue function. To re-iterate, that function is only called after the shouldChangeTextIn function returns true or false.
If there are any mistakes here or anything else someone else would like to add, feel free to let me know.
Happy programming!