Question

I have an NSArray of strings that I would like to animate with a simple fade in/out animation.

----------------------------------------------------------------------------------
|     fade in
|     String 1 ---> displayed in UILabel
|     fade out
----------------------------------------------------------------------------------

followed by

----------------------------------------------------------------------------------
|     fade in
|     String 2
|     fade out
----------------------------------------------------------------------------------

etc…

Each one holding it’s position for about 5 seconds before it continues to the next item in the array. I’m not sure where to start… I know how to perform animations but I’m not quite sure how to animate through an array of strings with a 5 second (non-thread-blocking) pause on each iteration. Any ideas?

UPDATE MY SOLUTION BASED ON ACCEPTED ANSWER

- (void)startTimer {
    arrayIndex = 0;

    NSArray *myarray = [alerts_dict allValues]; 
    breakingLabel.text = [myarray objectAtIndex:frameCount];

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    [UIView setAnimationDuration:1];
    breakingLabel.alpha = 1;
    [UIView commitAnimations];

    arrayIndex++;
    pauseTimer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:@selector(myFunction) userInfo:nil repeats:YES];
}

- (void)myFunction {    

   [UIView animateWithDuration:1 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^() {
       breakingLabel.alpha = 0;
   }
   completion:^(BOOL finished) {
       NSArray *myarray = [alerts_dict allValues]; 

       if (arrayIndex == [myarray count])
           arrayIndex = 0;

       breakingLabel.text = [myarray objectAtIndex:arrayIndex];

       arrayIndex++;

       [UIView animateWithDuration:1 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^() {
           breakingLabel.alpha = 1;
       } completion:nil];
   }];
}

Answer 1

You can do this pretty easily using block animations:

1. Animate label’s alpha down to 0.0
2. On completion: set its text to the new string and animate it’s alpha back to 1.0 (or original value, whatever it was)

This routine can be invoked repeatedly by an NSTimer timeout callback. Just instantiate a timer with interval 5.0, specify the callback and schedule it to run in the run loop like this:

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self
                  selector:@selector(timerFired:) userInfo:nil repeats:YES];

(...)

- (void)timerFired:(NSTimer *)timer
{
    // call the method to update the label with the next string in the array
    // or invalidate the timer if you've reached the end of array
}