textField should update as soon as a method is called

I am working on a project which deals with an examination paper. I display only 1 question at a time on the view. After the users answers the question a second question is displayed if the user swipes towards left hand side.

I have placed a textField to display the score at each point in time. I implemented it but my score gets updated only if the user navigates to the next q开发者_如何学编程uestion. My requirement is that as soon as the question is answered the score should be updated in the textField.

scoreField.text=[NSString stringWithFormat:@"%d",currentScore];

Is there any technique to do so whenever a question is answered? My paper has 20 questions and has 20 submit buttons so I cannot place the above code at each and every submit button action method. It would be ugly and not effective programming.

Please help if there is any way to solve my case.

Thanks in advance

If you understand your problem correctly then you don't want to set scoreField.text in every submit button handler. I am assuming that you are setting this when navigating to next question. You only need to update this when currentScore is changed. So I think it's better to create a setter for currentScore and update scoreField.text from that. Something like this:

- (void)setCurrentScore:(NSInteger)newScore {
    currentScore = newScore;
    scoreField.text=[NSString stringWithFormat:@"%d",currentScore];
}

And call setCurrentScore whenever you need to change the score. Or even better, you can use a setter property and write your own setter implementation.

This can be made really simple, and elegant. With a few assumptions:

• There is globally accessible model object that holds the score, for example +[Examination sharedExammination].
• The model object has a KVO (Key-Value-Observing) compatible property like score.
• You use a custom subclass of UILabel to display the score.

With these assumptions you can let your custom UILabel register for KVO changes to to the score property and update itself automatically. The implementation of the UILabel subclass would include something like this:

-(id)initWithFrame:(CGRect)frame 
{
    self = [super initWithFrame:frame];
    if (self) {
        [[Examination sharedExamination] addObserver:self
                                          forKeyPath:@"currentScore"
                                             options:0
                                             context:NULL];
    }
    return self;
}
-(void)dealloc 
{
    [[Examination sharedExamination] removeObserver:self
                                         forKeyPath:@"currentScore"];
    [super dealloc];
}
-(void)observeValueForKeyPath:(NSString*)keyPath 
                     ofObject:(id)object 
                       change:(NSDictionary*)change 
                      context:(void*)context
{
    if ([keyPath isEqualToString:@"currentScore"]) {
        scoreField.text = [NSString stringWithFormat:
                           @"Score: %d", [object currentScore]];
    } else {
        [super observerValueForKeyPath:keyPath
               ofObject:object
                 change:change
                context:context];
    }
}

Try this:

[self.view setNeedsDisplay];