shouldChangeCharactersInRange doesn't get the last number - objective-c

Question

I have this code that should catch exactly what the user types:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSLog(#"Catch -> %#",textfield.text);
}
But When the user digit the letter A, the console return me ('null'), When the user digit the letter AB, the console return me only the letter A, in this case the method shouldChangeCharactersInRange doesn't return the last letter that user types.
To change this I try to change my code to:
NSLog(#"Catch -> %#",string);
In this case, the console shows me only the last number. How can I solve this problem and pick the complete sentence that user digit?

Answer 1

This method is called BEFORE the text field has changed. If you speak English, you would have already known this just by reading the method name, one of the big advantages of Cocoa...
This method gives you a chance to say "NO, don't change the text in this text box!" or to change the text in the box before the change is made, or to change the text that will be added before it's added.
textfield.text won't reflect the change until after this method returns.
To catch the END of editing events for a textfield, put this in your viewDidLoad:
[yourTextField addTarget:self
action:#selector(textFieldDidChange:)
forControlEvents:UIControlEventEditingChanged];
Where yourTextField is a reference to the text field of interest.
Now write the method:
- (void)textFieldDidChange:(UITextfield *)textfield {
NSLog(#"Catch -> %#", textfield.text);
}

Answer 2

This delegate method for me usually starts out like this:
- (BOOL)textField:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
NSString *candidateString = [textView.text stringByReplacingCharactersInRange:range withString:text];
Now, candidateString will contain what you expect. It's done this way so that any manner of input (even a paste into the middle of the text) can be understood before and after the text field's text is updated