clean up gesture recognizers

[myeyesareblind]

I got a weird crash when I changed collectionViewFlowLayout dynamically. Current version leaves gestures alive, so when the collectionView is tapped, gestureRecognizer will send message to zombie.

[bartoszhernas]

I have the same issue, but your fix is not helping. I am setting this layout in Storyboard and then changing it dynamically and with your fix its still crashing.

[lxcid]

Do you have a demo project that demonstrate this? If you have I can review it.

[bartoszhernas]

If you add to your example something like

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    self.collectionView.collectionViewLayout = [LXReorderableCollectionViewFlowLayout new];
    self.collectionView.collectionViewLayout = [LXReorderableCollectionViewFlowLayout new];
}

It will crash then

[lxcid]

Noted. Thanks. Will give it a try and get back to you guys.

[myeyesareblind]

@bartg , thank you, my first commit didn't fix the issue. The problem is that in dealloc, collection view is already nil, so the gestures still exists.

[myeyesareblind]

I won't do that, feel free to contribute.

[lxcid]

@bartg That was what I was thinking as well.

I was thinking of the following changes but some of it I'm currently not confident enough about them. I'm tagging LOW, MED, HIGH as an indication of my confidence level of each point.

• [LOW] properties holding gesture recognisers should be change to weak, from strong.
  The reason for this is that the ownership of the gesture recognisers should not be shared between the layout and the collection view. It is technically owned by the collection view and reference from the layout. But the code written in place do not expect these properties to be weak in nature, and the change might cause unexpected behaviour. So I'm letting it slip.
• [MED] Introduces -[LXReorderableCollectionViewFlowLayout tearDownCollectionView] which wraps @bartg solution but with some if guards. (I prefer to be extra caution) It should be the opposite of -[LXReorderableCollectionViewFlowLayout setupCollectionView].
• [MED] Have -[LXReorderableCollectionViewFlowLayout tearDownCollectionView] be called in both dealloc and KVO of collectionView properties.

[myeyesareblind]

@lxcid I like 2-3, this way you are making it obvious that there is some important code to be run on dealloc.

[lxcid]

Thanks @myeyesareblind, didn't realise its your changes. I have pull from your repro and work on top of your changes. :)

https://github.com/lxcid/LXReorderableCollectionViewFlowLayout/commit/337711bab35e5b6a5035d5f545df8b79ed4b3a20

Could you help me review if this look good? My initial test seems to work. Let me know if you find any quirkiness. If all is well I'll merge to master and release a tag.

/cc @bartg

[myeyesareblind]

It's good

[lxcid]

Thanks for the help! Its merged!