Loading ViewController from xib file

Question

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?

Asymptotic

can you see the full code – Babyblueeyes

@Asymptotic Check all the outlets you have created and connected with components. Make sure there should not be any exclamation mark in the Outlets in connection inspector in your .xib file. – Lawgiver

bluenowhere: did you find your answer? – Pademelon

I believe the first two methods initialize your "MyViewController" class as a UIViewController and don't hook up the outlets and actions correctly, so the app crashes trying to find them. Initializing with your class' constructor hooks up the class outlets to the nib so everything works as it should. – Spiral

Answer 1

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)

Fadiman

@Woodstock: Kind of! It is the correct answer to the question 'How do I load the layout of a ViewController from a XIB file'. However, the original question is ambiguous as OP doesn't seem to distinguish between (1) loading the layout (View) of a programmatically instantiated ViewController from a XIB, and (2) loading the ViewController instance itself from the XIB. AechoLiu's answer is the correct answer to the second interpretation :-) – Readiness

if your vc name is same as xib file you can use (nibName: nil, bundle: nil) and it will work – Stainless

I get error loaded the "..." nib but the view outlet was not set. – Stray

Answer 2

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()

Secure

This is a great approach to avoid a bunch of duplicate code! You should note that the name of the nib file needs to be the same as the name of the class. – Dingus

Of course. The name of the nib file needs to be the same as the name of the class. – Secure

Answer 3

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.

Lauder

Answer 4

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)
        }

Tarlatan

Answer 5

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()

Pad

Answer 6

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 :)

Manuelmanuela

Answer 7

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.

Glossal

Please don't just put code explain what was mistake and how your code helps to solve it :) – Hawthorne

Yeah, as you can see the different skill for writing code. Some time it won't allow to initialize within one lines of code. – Glossal

Answer 8

Updated for Swift 5

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

Laurenelaurens

It is returning a nil value for myVC, something is missing in the code, try to add a full code snippet instead :) – Serilda

Answer 9

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.")
    }
}

Soria

ViewControllerInXib doesn't exists. – Penurious

Answer 10

@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.

Inkblot

Answer 11

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()
}

}

Deceive

Answer 12

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.

Melanymelaphyre

Answer 13

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)

Panarabism

follow #47383066 for more information. – Panarabism

Answer 14

Works this in Swift5

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

Carrycarryall

No difference using Swift 5 compared to the previous version. This is the same as the other answers. – Botello