Cococa Touch - Verifying each character inputed

I want to have the user t开发者_运维技巧ype in something. And I want to verify each character inputed. How could I do this? I want it to be in real time. So as its typed its being verified and color coded.

You could compare what I want to do to an programmers IDE how it checks the syntax as you type it.

Any help is appreciated!

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Connect the UITextField delegate to the app delegate and do something like:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    if([string isEqual:@"b"]) {
        // User typed 'b'
        // Insert string with specific color
        // [...]
    } else {
        // User typed something else
        // Insert string without specific color
        textField.text = [textField.text stringByReplacingCharactersInRange:range withString:string];
    }
    return YES;

}