iPhone SDK: How come the following code only animates first frame?

Question

Hello, I have been trying to animate using an NSTimer and I've set up my code like this:

- (IBAction)startClick:(id)sender{

animationTimer = [NSTimer scheduledTimerWithTimeInterval:(.1/25.0) target:self selector:@selector(tick) userInfo:nil repeats:YES];

}

- (void)tick{
    [self animatePig];
}

- (void)animatePig{

    UIImage *pigImage1 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0004.png" ofType:nil] ];
    UIImage *pigImage2 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0005.png" ofType:nil] ];
    UIImage *pigImage3 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0006.png" ofType:nil] ];
    UIImage *pigImage4 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0007.png" ofType:nil] ];
    UIImage *pigImage5 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0008.png" ofType:nil] ];
    UIImage *pigImage6 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0009.png" ofType:nil] ];
    UIImage *pigImage7 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0010.png" ofType:nil] ];
    UIImage *pigImage8 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0011.png" ofType:nil] ];
    UIImage *pigImage9 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0012.png" ofType:nil] ];
    UIImage *pigImage10 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0013.png" ofType:nil] ];
    UIImage *pigImage11 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0014.png" ofType:nil] ];
    UIImage *pigImage12 =[UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"gordonapple0015.png" ofType:nil] ];

    if(gordon.image == pigImage1)
     gordon.image = pigImage2;
    else if(gordon.image == pigImage2)
     gordon.image = pigImage3;
    else if(gordon.image == pigImage3)
     gordon.image = pigImage4;
    else if(gordon.image == pigImage4)
     gordon.image = pigImage5;
    else if(gordon.image == pigImage6)
     gordon.image = pigImage7;
    else if(gordon.image == pigImage7)
     gordon.image = pigImage8;
    else if(gordon.image == pigImage8)
     gordon.image = pigImage9;
    else if(gordon.image == pigImage9)
     gordon.image = pigImage10;
    else if(gordon.image == pigImage10)
     gordon.image = pigImage11;
    else if(gordon.image == pigImage11)
     gordon.image = pigImage12;
    else
     gordon.image = pigImage12;


}

Does anyone know why this only animates the first frame? The problem's probably very simple to fix, i'm just too much of a noob in iPhone development to notice. ----------Edit----------

Okay, I have got my NSTimer to work correctly, and my next step was to stop my animation repeating over and over, so I invalidated my timer like this:

[animationTimer invalidate];

And now, when the timer is called again it doesn't work, so how would I validate it again? (re-instantiate it I think)

(BTW I Have set up another SO question for this)

My code as of now:

- (IBAction)startClick:(id)sender{

animationTimer = [NSTimer scheduledTimerWithTimeInterval:(1.00/30.00) target:self selector:@selector(tick) userInfo:nil repeats:YES];

} - (void)tick{ [self animatePig]; } - (void)animatePig{

UIImage *pigImage1=[UIImage imageNamed:@"gordonapple0004.png"];
UIImage *pigImage2=[UIImage imageNamed:@"gordonapple0005.png"];
UIImage *pigImage3=[UIImage imageNamed:@"gordonapple0006.png"];
UIImage *pigImage4=[UIImage imageNamed:@"gordonapple0007.png"];
UIImage *pigImage5=[UIImage imageNamed:@"gordonapple0008.png"];
UIImage *pigImage6=[UIImage imageNamed:@"gordonapple0009.png"];
UIImage *pigImage7=[UIImage imageNamed:@"gordonapple0010.png"];
UIImage *pigImage8=[UIImage imageNamed:@"gordonapple0011.png"];
UIImage *pigImage9=[UIImage imageNamed:@"gordonapple0012.png"];
UIImage *pigImage10=[UIImage imageNamed:@"gordonapple0013.png"];
UIImage *pigImage11=[UIImage imageNamed:@"gordonapple0014.png"];
UIImage *pigImage12=[UIImage imageNamed:@"gordonapple0015.png"];
UIImage *pigImage13=[UIImage imageNamed:@"gordonapple0016.png"];


if(gordon.image == pigImage1)
 gordon.image = pigImage2;
else if(gordon.image == pigImage2)
 gordon.image = pigImage3;
else if(gordon.image == pigImage3)
 gordon.image = pigImage4;
else if(gordon.image == pigImage4)
 gordon.image = pigImage5;
else if(gordon.image == pigImage5)
 gordon.image = pigImage6;
else if(gordon.image == pigImage6)
 gordon.image = pigImage7;
else if(gordon.image == pigImage7)
 gordon.image = pigImage8;
else if(gordon.image == pigImage8)
 gordon.image = pigImage9;
else if(gordon.image == pigImage9)
 gordon.image = pigImage10;
else if(gordon.image == pigImage10)
 gordon.image = pigImage11;
else if(gordon.image == pigImage11)
 [animationTimer invalidate];

else
 gordon.image = pigImage1;

}

Answer 1

There's no good way to know without seeing more code from you. How do you store "gordon"? What type is it? presumably some type of UIImageView?

However, your real problem (if I may go to a higher level) is your entire structure. Try something more like this:

// Interface file

NSMutableArray *pigImages;
int pigImageIndex;

// Implementation file

const int firstImageIndex = 4;
const int lastImageIndex = 15;
const int imageCount = (lastImageIndex + 1 - firstImageIndex);

- (void) initPigImages
{
    pigImages = [[NSMutableArray alloc] initWithCapacity: imageCount];
    for (int i = firstImageIndex; i <= lastImageIndex; ++i)
    {
        [pigImages addObject: [self makePigImageWithIndex: i]];
    }
    pigImageIndex = 0;
}

- (UIImage*) makePigImageWithIndex: (int) imageIndex
{
    NSString *imageName = [NSString stringWithFormat: @"gordonapple%4d.png", imageIndex]; // Formatting may be a little off.
    return [UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource: imageName ofType: nil]]];
}

- (void )animatePig
{
    if (pigImageIndex < imageCount)
    {
        gordon.image = pigImages[pigImageIndex++];
    }
}

Answer 2

You're going about it the hard way.

• Create a UIImageView and put it on the screen.
• Load your images into an NSArray.
• Set the UIImageView's animationImages property to the array.
• You can adjust the animationDuration and animationRepeatCount properties as well.
• When user presses the start button, call the startAnimating method of the image view.

You don't need the timer nor the manual frame advancing code.

Answer 3

To restart your timer you can use -[NSRunLoop addTimer:forMode:] or just release and create a new timer each time.