IBOutlets from xib are not initialised if I run an app on iOS8 Simulator

Question

I have build an app using XCode 7 GM (base SDK - iOS9). It works perfectly if I run it on iOS 9 Simulator but if I try to run it on iOS8 it fails here:

@IBOutlet weak var collectionView: UICollectionView!

override func viewDidLoad() {
    super.viewDidLoad()
    navigationItem.title = NSLocalizedString("Home", comment: "Home")
    collectionView.registerNib(UINib(nibName: "PTHomeCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "PTHomeCollectionViewCell")
}

with an error

fatal error: unexpectedly found nil while unwrapping an Optional value

because a collectionView is nil:

Of course I have doubled checked that connection in IB is established:

Could anyone please tell me why collectionView is nil here?

unexpectedly found nil kind of error mostly solve if you clean and run the app again. — Teja Nandamuri, Sep 17 '15 at 14:15

score 3 · Accepted Answer · edited May 23 '17 at 11:52

I was able to fix this issue by adding

override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    let name = NSStringFromClass(self.dynamicType).componentsSeparatedByString(".").last!
    super.init(nibName: nibNameOrNil ?? name, bundle: nibBundleOrNil)
}

to the view controller class. But why it works this way? Is there another way to fix this issue?

Update: It is an Swift view controllers feature that is very similar to a bug. Check Can't Load UIViewController XIB file in Storyboard in Swift and Are view controllers with nib files broken in ios 8 beta 5?

It is fixed in iOS 9.4 but if you need iOS 8 and earlier support you still need to use workarounds.

score 1 · Answer 2 · answered Apr 27 '16 at 14:08

1

This issue is highlighted in Matt Neuburg's book Programming iOS 8. This happens because iOS 8 expects xib names to be prefixed with module name which is the same as name of project in this case. For example, if you have MyViewController in your project MyProject, it will expect to find the xib named MyProject.MyViewController.xib. To workaround this, override nibName in your view controller:

override var nibName: String? { 
    return "\(self.dynamicType)"
}

answered Apr 27 '16 at 14:08

Alexander Doloz

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But will it work if I do not want to prefix all my xibs with the module name? – Avt Apr 27 '16 at 15:18
Yes. Just override `nibName` as I show and everything will be fine. – Alexander Doloz Apr 27 '16 at 15:40

score 0 · Answer 3 · edited May 23 '17 at 11:52

How are you instantiating your view controller?

Instantiating via viewController = MyViewController() will crash in iOS8.x when accessing the IBOutlets (though it works ok in iOS9.3, and presumably in iOS9.x)

Instantiating the view controller with viewController = MyViewController(nibName: "MyViewController", bundle: nil) should work no matter the version of iOS.

See this other posting for reference: All my IBOutlet are nil in viewDidLoad

IBOutlets from xib are not initialised if I run an app on iOS8 Simulator

3 Answers3