使用Xcode中的自定义键盘来限制UITextfield中的文本

Question

I just got a custom keyboard working. I wanted to put one last touch on the App and I can't figure it out. I want to limit the amount of text input. I have used the method....

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSLog(@"user is entering numbers");
NSUInteger newLength = [textField.text length] + [string length] - range.length;
return (newLength > 8) ? NO : YES;
}

But it never gets called. I can type on my actual keyboard and the text is limited to 8. But if I use my custom keyboard in the simulator, I can put numbers in forever. Any idea how to get this method called from my custom keyboard? Thanks!!

EDIT

In response to Kjuly's help. Here is some more of my code.

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
NSLog(@"textFieldDidBeginEditing");
if ([fahrenheit isFirstResponder]) 
{
    self.currentTextField = self.fahrenheit;
    celcius.text = @"";
    kelvin.text = @"";
    self.userIsEnteringANumber = NO;
}
else if ([celcius isFirstResponder])
{
    self.currentTextField = self.celcius;
    fahrenheit.text = @"";
    kelvin.text = @"";
    self.userIsEnteringANumber = NO;
}
else if ([kelvin isFirstResponder])
{
    self.currentTextField = self.kelvin;
    fahrenheit.text = @"";
    celcius.text = @"";
    self.userIsEnteringANumber = NO;
}
}

This method does get called when editing begins. But still the shouldChangeChararcterInRange method only gets called if I use my keyboard. My viewDidLoad method is

- (void)viewDidLoad
{
[super viewDidLoad];
[fahrenheit setText:@""];
[celcius setText:@""];
[kelvin setText:@""];
[fahrenheit setInputView:keyPad];
[celcius setInputView:keyPad];
[kelvin setInputView:keyPad];
fahrenheit.delegate = self;
celcius.delegate = self;
kelvin.delegate = self;
}

So thanks for all the help, I hope to get this figured out soon!

Answer 1

But it never gets called.

Add this after you've alloced the yourTextField :

[self.yourTextField setDelegate:self];

---

EDIT

Your -viewDidLoad: method should like:

- (void)viewDidLoad
{
  [super viewDidLoad];

  // you should alloc your text fields here or in |-init| method
  fahrenheit = [[UITextField alloc] initWithFrame:CGRectMake(...)];
  celcius    = [[UITextField alloc] initWithFrame:CGRectMake(...)];
  kelvin     = [[UITextField alloc] initWithFrame:CGRectMake(...)];
  [self.view addSubview:fahrenheit];
  [self.view addSubview:celcius];
  [self.view addSubview:kelvin];

  [fahrenheit setText:@""]; // you can set it to nil
  [celcius setText:@""];
  [kelvin setText:@""];
  [fahrenheit setInputView:keyPad]; // what's keyPad? It's your custom input view, uh?
  [celcius setInputView:keyPad];
  [kelvin setInputView:keyPad];
  fahrenheit.delegate = self;
  celcius.delegate = self;
  kelvin.delegate = self;
}

Answer 2

Well, I finally figured it out!! I found a post that said Xcode won't run the method shouldChangeCharactersInRange when using a custom keyboard. Something to do with Xcode not knowing if a button had one item on it or several. So that's why that method never was called. I then saw someone try to limit the text with another method that he created. This didn't work for me, because my custom keyboard, checks for decimals along with appending the number. So I came up with the following code and it works! My inputs are limited to 8 characters, I can still use my neg sign because that was a different method.

- (IBAction)buttonPressed:(UIButton *)sender 
{
NSString *button = [sender currentTitle];
NSRange decimalpoint = [self.currentTextField.text rangeOfString:@"."];
if (self.userIsEnteringANumber)
{
    if (currentTextField.text.length < 8)
    {
       if ([button isEqualToString:@"."] && decimalpoint.location != NSNotFound)
       {
           self.currentTextField.text = self.currentTextField.text;
       }else 
           self.currentTextField.text = [self.currentTextField.text stringByAppendingString:button];
    }else 
        self.currentTextField.text = self.currentTextField.text;
}else 
    {
    self.currentTextField.text = button;
    self.userIsEnteringANumber = YES;
    }
}

So thanks for everyone's help especially @Kjuly.