Loading ViewController from xib file

I had a MyViewController.swift and a MyViewController.xib presenting the layout of MyViewController.

I tried different methods to load this view controller including:

//1
let myVC = UINib(nibName: "MyViewController", bundle: nil).instantiateWithOwner(nil, options: nil)[0] as? MyViewController
//2
let myVC = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)[0] as? MyViewController
//3
let myVC = MyViewController(nibName: "MyViewController", bundle: nil)

The third one is the only successful initialisation, but the previous two are causing error:

Terminating app due to uncaught exception 'NSUnknownKeyException',

reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key XXX.

What's wrong with those loading methods?

4

14 Answers

Swift 3

let myViewController = MyViewController(nibName: "MyViewController", bundle: nil)
self.present(myViewController, animated: true, completion: nil)

or push in navigation controller

self.navigationController!.pushViewController(MyViewController(nibName: "MyViewController", bundle: nil), animated: true)

3

extension UIViewController { static func loadFromNib() -> Self { func instantiateFromNib<T: UIViewController>() -> T { return T.init(nibName: String(describing: T.self), bundle: nil) } return instantiateFromNib() }
}

Use it as the following:-

let testVC = TestVC.loadFromNib()

2

Notice the File's Owner. In your case, the File's Owner must be MyViewController, or its sub-class.

And the following code, if it executes in class Foo.

// If `self` is an instance of `Foo` class.
// In this case, `File's Owner` will be a `Foo` instance due to the `self` parameter.
let myVC = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)[0] as? MyViewController

It assigns self as owner. So, the File's Owner is Foo, not MyViewController. Then, for Foo class, those IBOutlet cannot be connected to Foo. So, it throws exception.

I had the same problem. The automatically generated xib had a UIView in it. You have to delete the view, add new view controller to the xib, set the view controller class to the one you want and then connect the outlets. After all of this you can use the codes provided above to get an instance of this view controller, like this:

if let menuVC = Bundle.main.loadNibNamed("MenuViewController", owner: nil, options: nil)?.first as? MenuViewController { menuVC.profileType = profileType vc.present(menuVC, animated: true, completion: nil) }

The problem is not with the methods...you have probably kept an outlet(XXX) connected for some uielement and have removed it from corresponding controller...I am adding example below...

the above button is connected to controller now but when i comment outlet

my app crashes

so try to find outlet(xxx) that is missing from viewcontroller but is in xib file.Hope it helps :)

You can use this small UIViewController extension

extension UIViewController { class func loadController() -> Self { return Self(nibName: String(describing: self), bundle: nil) //Or You can use this as well //Self.init(nibName: String(describing: self), bundle: nil) }
}

Use like this

let controller = CustomViewController.loadController()

Try below code,

//1

let nib = UINib(nibName: "MyViewController", bundle:nil)
myVC = nib.instantiateWithOwner(self, options: nil)[0] as? MyViewController

OR

myVC = nib.instantiateWithOwner(self, options: nil).first as? MyViewController

//2

let nib : NSArray = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)
myVC = nib.objectAtIndex(0) as? MyViewController

This will work.

2

Connect the UIButton with an @IBAction and add the following code to the action method to present a new UIViewController that is set up inside a .xib file.

@IBAction func handleButtonAction(_ sender: UIButton) { let viewControllerInXib = ViewControllerInXib(nibName: "ViewControllerXibName", bundle: nil) present(viewControllerInXib, animated: true)
}

To navigate via UINavigationController you should use this method:

@IBAction func handleButtonAction(_ sender: UIButton) { let viewControllerInXib = ViewControllerInXib(nibName: "ViewControllerXibName", bundle: nil) if let navigationController = navigationController { navigationController.pushViewController(viewControllerInXib, animated: true) } else { print("Navigation controller unavailable! Use present method.") }
}

1

@AechoLiu's answer is great. I had the same question and answered it with the below fix.

Problem:

let vc1 = NSViewController(nibName: YDNibIdentifier.myplainvc, bundle: nil)

Fix:

let vc1 = MyPlainViewController(nibName: YDNibIdentifier.myplainvc, bundle: nil)

I had accidentally cast my Nib file to the wrong Clas ( NSViewController ), despite having it connected correctly inside the .xib file.

Updated for Swift 5

 let myVC = Bundle.main.loadNibNamed("MyViewController", owner: self, options: nil)![0] as? MyViewController

1

public extension UIViewController {
static func loadNib() -> Self { func instantiateFromNib<T: UIViewController>() -> T { return T.init(nibName: String(describing: T.self), bundle: Bundle.init(for: Self.self)) } return instantiateFromNib()
}

}

This extension function didn't work for me.

static func loadFromNib() -> Self { func instantiateFromNib<T: UIViewController>() -> T { return T.init(nibName: String(describing: T.self), bundle: nil) } return instantiateFromNib()
}

It was throwing me

Could not load NIB in bundle: 'NSBundle ... with name 'UIViewController'

So, I changed it to this and got it working.

static func instantiateFromNib<T: UIViewController>() -> T { // It is going to return YourAppName.YourClassName let classDescription = classForCoder().description() // Replacing YourAppName with Empty string let nibFileName = classDescription.replacingOccurrences(of: "\(Bundle.main.infoDictionary?["CFBundleName"] as! String).", with: String()) return T.init(nibName: nibFileName, bundle: Bundle.init(for: Self.self))
}

Just keep that in mind your .xib file and your .swift class name should be the same for it to work.

I removed File owner’s class name and set that to the class name of first view. And then I had to set outlets to the components which I’m going to use.

Then I loaded that view class like

let myViewController = Bundle.main.loadNibNamed("MyViewController", owner: self, options: nil)?.first as! MyViewController
view.addSubview(myViewController)

1

Works this in Swift5

self.navigationController!.pushViewController(MyViewController(nibName: "MyViewController", bundle: nil), animated: true)

1

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