shouldChangeCharactersInRange returning old results iOS

Question

I am new to iOS. I have a viewcontroller for registration, it contains three UITextfields for Email,password, Confirm password and a UIButton. I have some validations, On success of those validation I have to enable signup button. I have implemented it through shouldChangeCharactersInRange, But it returns me old characters e.g.

I type a => It returns me ""
then 
I type ab => It returns a
then 
I remove b => It returns me ab

In actual it is:

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range  replacementString:(NSString *)string {
if ([textField.text length]>0) {
  [self enableSignUpButton];
}
   return YES;
}


-(void)enableSignUpButton {
if ([emailTextField.text length]>0 && [passwordTextfield.text length]>0 &&  [confirmPasswordTextfield.text length]>0)
        signUpButton.enabled=TRUE;
        return;
}
signUpButton.enabled=FALSE;
}

It is not getting the textfield value dynamically I think ? or ?

Help me to get out of this.

score 1 · Accepted Answer · answered Sep 26 '14 at 07:51

Handle text change event like this

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.textField addTarget:self 
                       action:@selector(textFieldDidChange:) 
             forControlEvents:UIControlEventEditingChanged];  
}

- (void)textFieldDidChange:(UITextField *)aTextField
{
    if ([textField.text length]>0)
    {
       [self enableSignUpButton];
    } else {
       // NOTE
       [self disableSignupButton];
    }
}

Anjaneyulu Battula · Answer 2 · 2014-09-26T08:41:51.803

if you want to get update text, you have to add one line in shouldChangeCharactersInRange method, in that tempStr will print your updated text

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

    NSString *tempStr = [textField.text stringByReplacingCharactersInRange:range withString:string];
    NSLog(@"updated Text: %@",tempStr);
    if ([tempStr length] > 0) {
        [self enableSignUpButton];
    }

    return YES;
}

score 0 · Answer 3 · edited Sep 26 '14 at 07:52

0

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

take a look at the name of this method. It is called "shouldChange" not "hasChanged". So when this method ist called, the textfields content is not updated yet but you can decide if the next change should happen.

Claus

edited Sep 26 '14 at 07:52

l0gg3r

8,864
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answered Sep 26 '14 at 07:44

Thallius

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Isn't there any delegate method that called after the Character change ?? – Muhammad Burhan Sep 26 '14 at 07:49
@MuhammadBurhan check my answer, I have also fixed bug of disabling (if user deletes back textfield) – l0gg3r Sep 26 '14 at 07:52

score 0 · Answer 4 · answered Sep 26 '14 at 07:50

You need to first append the new string in existing text and then compare the length

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSUInteger newLength = [textField.text length] + [string length] - range.length;
    if (newLength>0) {
       [self enableSignUpButton];
    }
   return YES;
}

shouldChangeCharactersInRange returning old results iOS

4 Answers4