xcode 4.2.1 - limiting character length in TextField - iphone

Question

I have been trying to limit a textField by many codes available out there in the internet but with no luck.
I have added UIViewController<UITextFieldDelegate> in my header file
and textField.delegate = self; in my viewDidLoad
and implemented the following fundtion in my .m file:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
return !([newString length] > 5);
}
this stil does not limit my text field. any idea?

Answer 1

Do it as following as it has been the exact duplicate of this
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSUInteger newLength = [textField.text length] + [string length] - range.length;
return (newLength > 5) ? NO : YES;
}

Answer 2

The replacement string is just the 1 character that was pressed, not the whole string so you need to add It to the current textfield.text before counting.
Your count is probably always 1 (or more if pasting a word)

Answer 3

I implement this in my code and it works:
This code eliminate all the letters only accept numbers, but like I delete the character, you could delete everything that its over length 5 and it keeps a nice effect that appears and disappears
- (void)textFieldDidBeginEditing:(UITextField *)textField {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(textChanged:) name:UITextFieldTextDidChangeNotification object:textField];
}
- (void)textChanged:(NSNotification *)textField {
NSString *text = [[textField object] text];
NSString *last = [text substringFromIndex:[text length] -1];
NSArray *accept = [NSArray arrayWithObjects:#"0", #"1", #"2", #"3", #"4", #"5", #"6", #"7" , #"8", #"9", #".", nil];
for (int i=0; i<[accept count]; i++) {
NSLog(#"%#", [accept objectAtIndex:i]);
if (![last isEqualToString:[accept objectAtIndex:i]]) {
[[textField object] setText:[text substringToIndex:[text length]-1]];
}
}
}