bounce an image in to view

I have some code which works nicely and acts like a menu appearing when you click a button. I just want to animate slightly. So when it appears, it appears to bounce in. Here's the code which shows it

[UIView beginAnimations:@"theAnimation" context:NULL];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(yourAnimationHasFinished:finished:context:)];
[UIView setAnimationDuration: 0.3];
CGAffineTransform moveUp = CGAffineTransformMakeTranslation(0, -20);
scrollChangeClothing.transform = moveUp;
imgClothesMenuBg.transform = moveUp;
[UIView commitAnimations];  

[UIView beginAnimations:@"theAnimation" context:NULL];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(yourAnimationHasFinished:finished:context:)];
[UIView setAnimationDuration: 0.1];
CGAffineTransform moveUp = CGAffineTransformMakeTranslation(0, 0);
scrollChangeClothing.transform = moveUp;
imgClothesMenuBg.transform = moveUp;
[UIView commitAnimations];

the code above (I thought) should first show the image at -20 pixels start point, then settle back to it's original point.

I tried combining the transform commands but that didnt work either. Do I need to put the second animation in the setAnimationDidStopSelector?? So once it's finished, it will then bounce?

回答1:

I think your code doesn't work because the two animation blocks are coalesced behind the scene into one identity transform.

Try removing the UIView animation methods from the first block, leaving only the lines below. This should make your views "slide into position".

CGAffineTransform moveUp = CGAffineTransformMakeTranslation(0, -20); scrollChangeClothing.transform = moveUp; imgClothesMenuBg.transform = moveUp;
Try enclosing both blocks in an outer +beginAnimations:context:/+commitAnimations block if you do need to animate "sliding out".

回答2:

Yes, you should move your second animation block into the first's animationDidStop method.