如何在Swift中显示带有UICollectionView的弹出式UIViewController？

Question

The UIViewController with UICollectionView works fine if I launch it from storyboard. However, when I try to launch it like this:

let imagePicker = imagePickerControllerViewController()
imagePicker.modalPresentationStyle = .OverCurrentContext
presentViewController(imagePicker, animated: true, completion: nil)

It crashes on line:

collectionView.dataSource = self

The question is, how to show a UIViewController (that has a UICollectionView) modally properly?

Answer 1

Replaced :

let imagePicker = imagePickerControllerViewController()

With:

let imagePicker = storyboard.instantiateViewControllerWithIdentifier("imagePicker") as! imagePickerControllerViewController