how to validate a Text field to accept only Characters at run Time in iphone

i want to validate a text field to ac开发者_如何学运维cept only characters while typing in it.....

I use the following for integers but I guess you could easily modify it to scan for strings/chars (see NSScanner):

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

NSString *resultingString = [textField.text stringByReplacingCharactersInRange: range withString: string];

// This allows backspace
if ([resultingString length] == 0) {
    return true;
}

NSUInteger holder;
NSScanner *scan = [NSScanner scannerWithString: resultingString];

return [scan scanInteger: &holder] && [scan isAtEnd];
}

Don't forget to set the UITextField delegate appropriately :)