The app essentially transitions between two different UICollectionViewFlowLayouts in a UICollectionView. I've not had a single problem with the TLLayoutTransitioning class prior to iOS 9. Thanks so much for taking the time to make and share this, by the way! It's a life saver. :)

For some reason since updating to iOS 9 (app still compiled for 8+) the transition doesn't center the offset, and instead seems to throw the whole transition off now while transitioning from large to small layouts, as seen here:

Any thoughts what might've changed?

• Update Podfile deployment target to iOS 8.0 (required for dynamic frameworks)
• Add use_frameworks! to Podfile
• Bump deployment target in Examples.xcodeproj to iOS 8.0
• Run pod update to update Pods and reintegrate them as frameworks

See discussion on #19 for more details.

Hello, I am using your collectionview transition in my app and I appear to have a memory leak and xcodes profiler indicates it is here:

UICollectionViewTransitionLayout *transitionLayout = [self startInteractiveTransitionToCollectionViewLayout:layout completion:^(BOOL completed, BOOL finish) { UICollectionViewTransitionLayout *transitionLayout = [self tl_transitionLayout]; if ([transitionLayout conformsToProtocol:@protocol(TLTransitionAnimatorLayout)]) { idlayout = (id)transitionLayout; [layout collectionViewDidCompleteTransitioning:self completed:completed finish:finish]; } [self tl_setAnimationDuration:nil]; [self tl_setAnimationStartTime:nil]; [self tl_setTransitionLayout:nil]; [self tl_setEasingFunction:NULL]; if (completion) { completion(completed, finish); } [[UIApplication sharedApplication] endIgnoringInteractionEvents]; }];

I am unsure of how to fix this, can you help?

When using TLLayoutTransitioning as a CocoaPod where use_frameworks! is specified and Modules are enabled, the framework fails to build because of how the easing.h header from AHEasing is being imported:

Include of non-modular header inside framework module ‘TLLayoutTransitioning.UICollectionView_TLTransitioning’

This is easily resolved by changing the AHEasing import to a framework style import.

See http://blog.cocoapods.org/Pod-Authors-Guide-to-CocoaPods-Frameworks/ for further discussion.

Hello again,

I have a situation where if i rotate my device while performing a layout transition the app errors with the following error:

the collection is already in the middle of an interactive transition

So I was wondering if there was a way I could cancel the transition if one was in progress?

the demo can't find TLCollectionViewController.

TLCollectionViewController', superclass of 'CollectionViewController'; did you mean 'UICollectionViewController'?

did this file get misplaced from repo?

Cheers JP

Hi Tim,

I'm currently making use of your TLLayoutTransitioning class and it is really easy to use! Thanks a lot for developing this! Actually, I encountered a problem with transition with supplementary views. In my project, instead of only one section, I have two sections in the collection view, and for each section, there is a header view and a footer view. However, after applying your resizing example, the header view and footer view are gone after doing a layout transition (animate cells to be bigger.) I don't think this is an issue with your implementation, but I just have no idea how to accommodate supplementary views in your example (Maybe there is a way to fix it easily which I'm not aware of.). So, if at all possible, could you also add some header view/footer view in your resizing example so that I can study from it? I'm in desperate need of a way to make my project work...

Thanks a lot in advance!

Sincerely,

Frank

Many errors like Pods-TLIndexPathTools-prefix.pch:2:9: Could not build module 'UIKit' or CoreFoundation.h:11:10: Could not build module 'Darwin' occur when trying to run the Examples project for iOS 7.1 simulator in Xcode 5.1 (5B130a) straight from the repo, no modifications.

It is useful to be able to pass the progress, for example, to the cells during complex transitions. Previously the transition layout was using UICollectionViewLayoutAttributes by default instead of honouring the class defined by layoutAttributesClass

Hey Tim, thanks for creating this. It was working well for me when I had only one section in my collection view, but now with multiple sections I'm experiencing a crash during transitionToCollectionViewLayout:duration:easing:completion: that I wasn't experiencing with the stock setCollectionViewLayout:animated:completion: method.

The setup: I have a collection view that supports a transition between a 1-wide grid layout and a 4-wide grid layout. The cells in the collection view are sectioned by month (Sept 2014, August 2014, ...) and the content is paginated such that when the user scrolls to the bottom new content is requested from my API and appended to my dataSource (currently just calling reloadData instead of performing any insertion updates).

Steps:

1. Start with a 1-wide grid. Transition to a 4-wide grid. Technically there's still only 1 section at this point, because we're still in the first month of data.
2. Scroll down a few pages in the 4-wide grid until we've reached the next section.
3. Attempt to transition back to the 1-wide grid results in a crash at this line:

UICollectionViewLayoutAttributes *toPose = reverse
                    ? [self.currentLayout layoutAttributesForItemAtIndexPath:indexPath]
                    : [self.nextLayout layoutAttributesForItemAtIndexPath:indexPath];

Because self.nextLayout's layoutAttributesForItemAtIndexPath:indexPath returns nil when the section index > 0. The error is:

Uncaught exception: *** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]

It appears that when I transition from the 1-wide layout, there's only one section in existence. Then, after scrolling the 4-wide layout, there's multiple sections. Attempting to go back to the 1-wide layout, the crash occurs.

If I scroll through many sections while in the 1-wide layout, and then scroll back up, I'm free to transition between layouts since the number of sections in the 1-wide layout is in sync with the number of sections in the 4-wide layout.

Any idea how to fix this? I'd very much like to continue using your library.

Thanks!

This library is super helpful! Thank you so much! But I'm getting this bug suddenly:

"[UICollectionViewTransitionLayout setToContentOffset:]: unrecognized selector sent to instance 0x146f8360"

Specifically my stack trace breaks at the following line in your example:

"layout.toContentOffset = toOffset;"

If I comment it out, everything works fine, except, obviously, I no longer get that awesome offset during transitions. The problem, as best as I can tell, is that the following line of code is returning a [UICollectionViewTransitionLayout] and therefore isn't being properly typed to your [TLTransitionLayout] subclass for some reason:

"TLTransitionLayout *layout = (TLTransitionLayout *)[collectionView transitionToCollectionViewLayout:toLayout duration:2 easing:QuarticEaseInOut completion:nil];"

When I NSLog the 'layout' object, it's definitely a [UICollectionViewTransitionLayout] type, not [TLTransitionLayout]. And, obviously, the [UICollectionViewTransitionLayout] class doesn't have the property "toOffset" I need, hence the error I'm experiencing. I've searched all over since this problem popped up over 9 hours ago, and zero solutions have helped. I've ensured all headers are included with #import and the implementation files are all being compiled within the correct target. I've cleared all my Derived Data, etc. Even uninstalled and reinstalled Xcode. I'm certainly lost. It just stopped working suddenly. I know it must be PEBKAC, but I can't for the life of me figure out how that can be. :( Anyhow, thanks a bunch for any insight. It was spectacular when it was working for me. :)

The framework target needs to include the .m files.

Also, AHEasing needs to be added to Linked Frameworks and Libraries.

These changes are needed for the framework to be used with Carthage.

The AHEasing module referenced in the Cartfile does not work with Swift. The AHEasing umbrella header AHEasing.h does not include the other public headers in the AHEasing project.

Hi!

There seems to be a bounce effect when you complete an interactive transition, I'd like to replace that by just decelerating to final position without bouncing.

You can check this effect in the Example project, if you pinch and release it'll complete the interactive transition with a bounce effect going a bit further than final progress in some cases.

The workaround I found is to subclass TLTransitionLayout and override the setProgress:time: method limiting values to 0..1

- (void)setTransitionProgress:(CGFloat)transitionProgress time:(CGFloat)time
{
    [super setTransitionProgress:MAX(0, MIN(transitionProgress, 1.f)) time:MAX(0, MIN(time, 1.f))];
}

This does get rid for the bounce effect (it's no longer visible to the user) but the transition still takes some time to complete because it thinks it's bouncing.

Any idea how can I solve this issue?

Thanks in advance,

Nicolás.

I've noticed a jarring snap to an unintended position when the user lifts their fingers, ending the pinch gesture. After the layout snaps to the unintended position it will animate back to the expected layout.

Tim, thank you very much for building this. I'm playing around the resize example. When double clicking a cell, the program crashes. The error message is: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'the collection is already in the middle of an interactive transition'. I guess the beginIgnoringInteractionEvents and endIgnoringInteractionEvents calls should be added in collectionView:didSelectItemAtIndexPath:?