animateWithDuration makes swipeview choppy in indexDidChange.

[theprojectabot]

I have utlized a swipeView set as a subview in a viewcontroller, another subview on the viewcontroller is a backgroundImageView. I change the image of the backgroundImageView during the:

• (void)swipeViewCurrentItemIndexDidChange:(SwipeView *)swipeView

This works fine unless I have that image view do a coreanimation animateWithDuration. The scroll then becomes very chop as it finishes itself. I have found that setting the swipeview to: _swipeView.defersItemViewLoading = YES;

mitigates the problem, however now the transition is delayed... Here is my code for that method. Any possibility to make this work much smoother without setting the defer?

- (void)swipeViewCurrentItemIndexDidChange:(SwipeView *)swipeView
{
//update page control page
pageControl.currentPage = swipeView.currentPage;
[pageControl updateCurrentPageDisplay];

  _backgroundImageView.image = [_backgroundImages objectAtIndex:pageControl.currentPage];
[UIView animateWithDuration:0.3
                      delay:0
                    options: UIViewAnimationOptionTransitionCrossDissolve
                 animations:^{
                     //view.alpha = 1;
                     //if([view isKindOfClass:[WDTourItemView class]])
                     _backgroundImageView.image = [_backgroundImages objectAtIndex:pageControl.currentPage];
                 } completion:^(BOOL finished){}];
}

[nicklockwood]

Try doing the transition using core animation like this instead of [UIView animateWithDuration:]

CATransition *transition = [CATransition animation];
transition.type = kCATransitionFade;
transition.duration = 0.3;
[_backgroundImageView.layer addAnimation:transition forKey:nil];

_backgroundImageView.image = [_backgroundImages objectAtIndex:pageControl.currentPage];

[theprojectabot]

Thanks! I found a similar solution but found that the transition flickers... unless I place this infront of the transition:

if ([UIImagePNGRepresentation(self.image) isEqualToData:UIImagePNGRepresentation(image)]) {
    return;
}

but then I end up with the same choppy swipe transition.

[theprojectabot]

I believe the flicker is because the coreanimation is getting interrupted so it auto completes the transition and then starts a new CATransition and so that auto complete sets the imageview's image and a flicker occurs.

[theprojectabot]

This is because of the quasi-completion state that the control is in as I swipe left and right...

[theprojectabot]

I have tried removing all Animations before calling the CATransition just to clear things out but it doesnt aleviate the flicker.

[nicklockwood]

I'm pretty sure getting the UIImagePNGRepresentation is an incredibly slow and expensive operation. Why not just compare the image pointers directly? If you have multiple image objects containing the same image, you should really use some kind of caching to make sure that doesn't happen.