Can't use UICollectionView in UIInputViewController for keyboard extension

Question

I have created a UICollectionView subclass which I want to use to provide the keys in a UIInputViewController as a keyboard extension. But I have found that attempting to instantiate a UICollectionView will cause the keyboard to crash whenever the user switches to it. Thinking it might be something to do with my UICollectionView subclass, I tried replacing it with a plain UICollectionView, but this caused the same problem. I even tried just instantiating the object but not doing anything with it, as in the extract below, but it still crashed the keyboard.

//  KeyboardViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];

    UICollectionView *collect = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
}

I can't get any debugging on the keyboard, because the debugger attaches to the main app's process, so I can't tell what is causing the crash. I would really appreciate any input on whether it is possible to use a UICollectionView on a keyboard extension, and if so, how I can get around this issue.

Answer 1

It turns out that the problem was being caused by simply importing the header for the UICollectionView subclass, even though I didn't use it. When I removed the import, I was able to instantiate a plain UICollectionView and add it as a subview of the keyboard.

This meant I had to do some fairly nasty stuff to abstract the delegate and datasource methods into a separate class so that they would be reusable, but it works.