Caishen causing crash

[korovyev]

It seems something is keeping a strong reference to CardTextField and is not releasing it

It then still seems to be registered for some internal notification that tries to access its superview, which it might not have at that point, causing crash. (In our case this is caused by a call to .setContentOffset(.. on a collectionView)

Heres the call stack

And heres a screenshot of the memory graph showing the textfields still in memory after the view controller in which they reside is released

Heres a sample project demonstrating the crash:
CaishenCrash.zip

Steps to reproduce in the demo project:

• Build & Run
• Tap button labelled "push vc"
• On the next viewcontroller, do not tap in the CardTextField (doing so prevents the crash ... ? )
• Tap button labelled "back"
• Tap button labelled "crash"
• Observe crash

Also, in our crashlytics data, this only seems to be happening on iOS 11 too, for some reason.