Could not instantiate class named IBNSLayoutConstraint

Question

I\'m using XCode6 beta and trying out Swift. When I put some auto layout constraints in a view controller the app crashes with the following error: Terminating app

Answer 1

What ended up happening to me was that I cut a subview inside of Interface Builder to copy it into another xib. This left the subview in original xib Interface builder with it being greyed out. After removing the subview from it's original place (by selecting and deleting). I was able to get rid of the error.

Answer 2

I had this issue when I had a button in a custom UICollectionViewCell, and had some of its constraints as IBOutlets on that class. I moved the button from the cell to the parent view controller and the IBOutlets were still referenced in the cell but didn't actually exist on the cell so blew everything up. Just needed to remove those IBOutlets and everything worked fine again!

Answer 3

This might not be necessarily a constraint problem. For me it was caused by not having checked "Installed" for a size class that was applying to my layout, see here

Answer 4

There was some problem with using size classes. I disabled that option from the storyboard properties and use only auto layout. It wasn't such a big problem since the app is iPhone only.

Answer 5

I had the same problem just now and the following worked for me.

I released a working version of my app to the App Store, came back to work on it again a few days later tapping onto one my tabs in the UITabBarController it crashed with the error:

Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named IBNSLayoutConstraint'

I didn't have any placeholder layout constraints that I was aware of or constraint outlets that shouldn't have been defined.

The solution for me was to simply turn size classes off and keep size class data for iPhone (App is only for iPhone). This must've deleted anything I'd missed in the size classes. I want size classes so I turned them back on and the app just worked again.

Answer 6

There is an option in the inspector window when you select the xib file that will not use the constrains under "Show file the inspector" in the inspector called "Use autolayout".