Thanks Alex, I have set an exception breakpoint but it never fires - and I will experiment with popping the second view controller programmatically and scrolling up.
I think this has to do with my elementary understanding of how UICollectionViews are reused in this type of transition animation - I've learned, for instance, that the datasource isn't actually changing (as part of "useLayoutToLayoutNavigationTransitions"). A tangental point I'm better understanding is that this property really just causes collection view controller push transitions to use the 'pushed' controller's layout ... (ie: the datasource is ignored). For example, tapping on a particular picture in a grid and pushing a new collection view controller on the stack might not actually change the existing picture data but does potentially reflow the layout - like, could make the selected picture huge. Yes, I am thinking that is probably the purpose of setting this particular property. Thanks again for looking and replying! -Luther On Wed, May 20, 2015 at 11:42 AM, Alex Zavatone <z...@mac.com> wrote: > What if you issue the back programatically and then scroll up? > > It would be interesting to see just what gets unwired here. > > Have you set an exception breakpoint to tell you exactly what is breaking? > > On May 20, 2015, at 12:46 AM, Luther Baker wrote: > > > I've got a simple iOS project consisting of 2 collection view controllers > > and a navigation controller. > > > > Tapping any item in the first collection view simply pushes the second > > collection view on the stack. > > > > Problem is, when I tap "< Back" and then manually scroll up ... the app > > crashes with a EXC_BAD_ACCESS error in main. > > > > Nothing is logged ... and the stack in the thread looks something like > > > > 0 objc_msgSend > > 16 UIApplicationMain > > 17 main > > 18 start > > 19 start > > > > with 17 main highlighted. > > > > ///// > > > > In the code, FirstViewController and SecondViewController are almost > > identical save for one line. I am specifically looking at what line 24 in > > SecondViewController does to the push transition. > > > > self.useLayoutToLayoutNavigationTransitions = YES; > > > > Upon running, the collection view "push" animation looks fine - and the > "< > > Back" button actually works ... but once I get back to > FirstViewController, > > the original colors never come back. In addition, when I scroll up, I get > > the error listed above. > > > > I've thrown together a small project to demonstrate: > > https://github.com/LutherBaker/CollectionViewDemo > > > > Thoughts? It feels like I'm not referencing something I should be ... > > > > Thanks, > > -Luther > > > > PS: I think you may ignore this but note that when you initially select > an > > item in the FirstViewController and "push" - the console spits lots and > > lots of > > > > *Snapshotting a view that has not been rendered results in an empty > > snapshot. Ensure your view has been rendered at least once before > > snapshotting or snapshot after screen updates.* > > which I assume is simply a bug or non-relevant logging accidentally left > in > > the framework. > > _______________________________________________ > > > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > > > Please do not post admin requests or moderator comments to the list. > > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > > > Help/Unsubscribe/Update your Subscription: > > https://lists.apple.com/mailman/options/cocoa-dev/zav%40mac.com > > > > This email sent to z...@mac.com > > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
