Question

I have created a UICollectionView and would like to have all the cells shake like the edit mode of the springboard on the iPhone. I have created my shake code but don’t know how to implement it. I have custom cells so I assume it goes in there but don’t know how it gets implemented. Thank You.

#define degreesToRadians(x) (M_PI * (x) / 180.0)
#define kAnimationRotateDeg 0.5
#define kAnimationTranslateX 1.0
#define kAnimationTranslateY 1.0

//startJiggling

int count = 1;
CGAffineTransform leftWobble = CGAffineTransformMakeRotation(degreesToRadians( kAnimationRotateDeg * (count%2 ? +1 : -1 ) ));
CGAffineTransform rightWobble = CGAffineTransformMakeRotation(degreesToRadians( kAnimationRotateDeg * (count%2 ? -1 : +1 ) ));
CGAffineTransform moveTransform = CGAffineTransformTranslate(rightWobble, -kAnimationTranslateX, -kAnimationTranslateY);
CGAffineTransform conCatTransform = CGAffineTransformConcat(rightWobble, moveTransform);

    self.transform = leftWobble;  // starting point

    [UIView animateWithDuration:0.1
                          delay:(count * 0.08)
                        options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionRepeat | UIViewAnimationOptionAutoreverse
                     animations:^{ self.transform = conCatTransform; }
                     completion:nil];

Answer 1

If you put you’re code in a method called startJiggling in your custom cell, then you could call this method in your controller:

[self.collectionView.visibleCells makeObjectsPerformSelector:@selector(startJiggling)];

That ensures that all visible cells will start jiggling.

Then I’d also set some flag indicating that your cells should jiggle and test for that in collectionView:cellForItemAtIndexPath:. If YES, then call your method.