unexpectedly found nil while unwrapping an Optional value (swift)

Question

I get the error in the title while trying to change the text of a label which is part of the Page class (a subclass of UIViewController)

@IBAction func StartButton(sender: AnyObject) { for quote in quoteList { var newPage = Page() //error is on the next line: newPage.Label.text = quote pageArray!.append(newPage) } }

}

and here is the Page class:

class Page : UIViewController{ var index: Int = 0 var parent: PageArray? override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } @IBOutlet weak var Label: UILabel! @IBAction func previousButton(sender: AnyObject) { } @IBAction func gotoListButton(sender: AnyObject) { } @IBAction func nextButton(sender: AnyObject) { }

}

I am new when it comes to swift programming, and iOs in general; I apologise if a similar question has already been asked. I searched first, but didn't find a solution that worked for me. I suspect the problem is with the initialization of newPage, and tried doing it a few different ways, but I can't seem to get it right. My question is what exactly am I doing wrong, and how can I fix it?

EDIT: Got it working like this (by working I mean not crashing and doing nothing):

 @IBAction func StartButton(sender: AnyObject) { var pageArray: PageArray = PageArray() for quote in quoteList { var newPage = Page(nibName: "Page", bundle: nil) if newPage.Label != nil { newPage.Label.text = quote } pageArray.append(newPage) } }

It seems certain now that newPage.Label is nil.

I have the same problem. I tried removing weak from @IBOutlet but that doesn't help. However all the non-IBOutlet vars (e.g. index, parent, etc) are accessible. It has to do with how these objects are instantiated (or not) from the storyboard/XIB file. Still digging. — AMC08
– AMC08, Commented Jul 16, 2015 at 17:58

Community · Accepted Answer · 2017-05-23 12:16:42Z

4

Well, pageArray is probably nil and with ! you are pretending that it is not.

Instantiating pageArray should solve your issue.

You can check the first answer here to learn more about question and exclamation marks in swift

EDIT:

Your problem might also come from your controller initialization, you might want to try:

let mystoryboard:UIStoryboard = UIStoryboard(name: "storyboardName", bundle: nil) var newPage:Page = mystoryboard.instantiateViewControllerWithIdentifier("idYouAssigned") as! Page

edited May 23, 2017 at 12:16

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answered Jul 16, 2015 at 16:28

streem

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12 Comments

Xebeq Over a year ago

That may be a problem, but it isn't the only one. I am getting the error before that, on this line: newPage.Label.text = quote

streem Over a year ago

@Xebeq Do you have a xib file linked to PageView ? If so i believe it is not loaded and Label is always nil. You might want to use NSBundle.mainBundle().loadNibNamed. If you can confirm you have a xib file i'll detail my answer

streem Over a year ago

Just realized, it is a viewcontroller. Init should be made with nib name. I've edited my answer.

Xebeq Over a year ago

I tried that before. For some reason, after I do this it thinks that newPage and pageArray are both strings (??). Deleting the next two lines and writing them again fixes this, but I still get the original error in the same place.

Xebeq Over a year ago

Also, the only .xib file in my project is LaunchScreen.xib and I do not believe it is linked to PageView.

|

Long Pham · Accepted Answer · 2015-07-17 11:24:27Z

0

I knew your problems. When you load a ViewController from Nib. Actually It's take a delay time until your ViewController has been loaded.

This code below help your ViewController load immediate.

@IBAction func StartButton(sender: AnyObject) { var pageArray: PageArray = PageArray() for quote in quoteList { var newPage = Page(nibName: "Page", bundle: nil) let _ = newPage.view // A trick. It's help your view load immediate // Your Page has been loaded. newPage.Label.text = quote pageArray.append(newPage) }

answered Jul 17, 2015 at 11:24

Long Pham

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3 Comments

Xebeq Over a year ago

This earns me another error: 2015-07-17 15:18:24.363 Quotes[3277:855732] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle </Users/user/Library/Developer/CoreSimulator/Devices/319D819D-C653-4AAF-ADDB-0514A8F055AE/data/Containers/Bundle/Application/042EE69B-E6D2-4CEF-A2D3-B1C438533DD1/Quotes.app> (loaded)' with name 'Page'' *** First throw call stack:

Long Pham Over a year ago

Do you try rename something like this? stackoverflow.com/questions/12722461/…

Xebeq Over a year ago

Well, nevermind. A combination of this and Justa's suggestion seems to have fixed it. No errors now, nothing's nil. Thanks! (time to move on to new exciting problems)

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