How to remove non numeric characters from phone number in objective-c?

Question

This is my first attempt to make an ios app.

I\'m using people picker to ask the user for a phone number, but when it retrieves with the code below, my NSStrin

Answer 1

I would use Regular expression to validate the phone number instead of killing myself to make a custom keyboard, which functions can be changed by iOS updates. So, allow all characters and validate inside the code.