Simple Animation Problem

[robotkid249]

Hello fellow developers,

I am trying to make an application where, when you launch the app and image starts to rotate automatically after launch. For some reason the way I am doing it, it needs a button or something to rotate, but I want it to rotate automatically. Maybe I have to take it out of the IBAction.. Or I don't know. I am pretty new to programming. Any help would be AWESOME!

It's simple code. The .h sets up the image and - (IBAction)rotate; The .m then does:

- (IBAction)rotate {
    
    // starts the animation
    [UIView beginAnimations:nil context:NULL];
    // sets the time before animation occurs
    [UIView setAnimationDelay:0];
    // sets the length of the animation
    [UIView setAnimationDuration:2.0];
    [UIView setAnimationRepeatCount:3]; //spin it 3 times. 
    // 3.14 is pi. -3.14 would be counter clockwise
    CGAffineTransform transform = CGAffineTransformMakeRotation(3.14/2);
    //square is the UIImageView getting rotated
    square.transform = CGAffineTransformRotate(transform, 3.14/2);
    // ends animation
    [UIView commitAnimations];
}

[Domele]

Make it void and call the method in viewDidLoad.

[robotkid249]

Thanks I fixed it, but I have more questions.

[robotkid249]

Now here is the problem. I did exactly what you said and put the animation code inside of the - (void)viewDidLoad and the spin animation starts automatically like I wanted it to. However, every time the image gets back to 0˚, it slows down and then speeds back up... Is there anyway I can get it to smoothly rotate? Thanks!

[Duncan C]

Originally Posted by robotkid249

Now here is the problem. I did exactly what you said and put the animation code inside of the - (void)viewDidLoad and the spin animation starts automatically like I wanted it to. However, every time the image gets back to 0˚, it slows down and then speeds back up... Is there anyway I can get it to smoothly rotate? Thanks!

Animations use ease-in-ease-out timing by default. Add the following line between your beginAnimations and commitAnimations:

[UIView setAnimationCurve: UIViewAnimationCurveLinear];

Do a search in the XCode docs for "setAnimationCurve". The documentation explains it pretty well.

[Domele]

It technically doesn't matter but I meant make the method you had void instead of IBAction (also void but if you aren't using it in Interface Builder take it out) and call the method in viewDidLoad.

[robotkid249]

@ Duncan C

Thanks so much. I did exactly what you said and it worked but... When the image rotates, it goes 360˚ but when it gets to around 357˚ it skips. It is not a fully smooth transition. Any suggestions?

- (void)viewDidLoad
{
    
    [super viewDidLoad];
    
    // starts the animation
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    // sets the time before animation occurs
    // sets the length of the animation
    [UIView setAnimationDuration:4.0];
    [UIView setAnimationRepeatCount:1e100f]; //spin it forever.
    // 3.14 is pi. -3.14 would be counter clockwise
    CGAffineTransform transform = CGAffineTransformMakeRotation(3.14/2);
    //bluegoal is the UIImageView getting rotated
    bluegoal.transform = CGAffineTransformRotate(transform, 3.14/2);
    // ends animation
    [UIView commitAnimations];
    

    
    // Do any additional setup after loading the view from its nib.
}

[jbernhardt]

The following code works but "transform" jumps into position while "transform2" rotates to position. I want them to both rotate to position.

The code is in a method called by didLoad.

Any help would be greatly appreciated.
Thanks.

    distRad = distDeg * 3.14157 / 180;
    [UIView beginAnimations:nil context:NULL];
    
    
    [UIView setAnimationDuration:4.0];
    [UIView setAnimationRepeatCount:100000]; //spin it forever.
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    CGAffineTransform transform = CGAffineTransformMakeRotation(distRad);
   
    
    fTailMove.transform = transform;
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    CGAffineTransform transform2 = CGAffineTransformMakeRotation(-distRad);
    fTailMove.transform = transform2;
    [UIView commitAnimations];

[Duncan C]

Originally Posted by jbernhardt

The following code works but "transform" jumps into position while "transform2" rotates to position. I want them to both rotate to position.

The code is in a method called by didLoad.

Any help would be greatly appreciated.
Thanks.

    distRad = distDeg * 3.14157 / 180;
    [UIView beginAnimations:nil context:NULL];
    
    
    [UIView setAnimationDuration:4.0];
    [UIView setAnimationRepeatCount:100000]; //spin it forever.
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    CGAffineTransform transform = CGAffineTransformMakeRotation(distRad);
   
    
    fTailMove.transform = transform;
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    CGAffineTransform transform2 = CGAffineTransformMakeRotation(-distRad);
    fTailMove.transform = transform2;
    [UIView commitAnimations];

You also asked this same question in a new thread.

DON'T DO THAT! It's maddening, and will get you blackballed if you do it repeatedly.

[jbernhardt]

Originally Posted by Duncan C

You also asked this same question in a new thread.

DON'T DO THAT! It's maddening, and will get you blackballed if you do it repeatedly.

I apologize for the double post. After posting on this thread, I thought this thread might be closed and then created a new one.

Thanks for your help.