Making outlet for the object from a xib file

Question

I am having a Hint.xib file where I have few elements (label, image view and a button). And I have a class called Hint, which is the subclass of a UIView and which loads this xib.

Here is how Hint class implementation looks:

import UIKit

@IBDesignable

extension UIView {
    class func fromNib<T : UIView>() -> T? {
        guard
            let nibs = Bundle(for: self).loadNibNamed(String(describing: self), owner: nil, options: nil),
            let nib = nibs.first
            else {
                return nil
        }

        return nib as? T
    }
}

class Hint:UIView {
    @IBOutlet weak var hintLabel: UILabel! 
    private func setup(){

        if let view = Hint.fromNib(){
            self.addSubview(view)
            view.frame = self.bounds
        }
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        setup()
    }


    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()

        setup()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)

       setup()
    }
}

Current Setup

On a storyboard, currently, I've added one view controller, and I have dragged a UIView inside of that view controller's view. After that, I set its custom class to Hint . Also I am using @IBDesignable directive and have overriden prepareForInterfaceBuilder() to have everything rendered in design, and this all works until I try to make an outlet for a label ( hintLabel ) that is a part of a Hint.xib file.

I am getting next error:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[< NSObject 0x60000001f8a0 > setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key hintLabel.'

I've selected my Hint.xib file -> File's Owner, and checked if everything is okay in Identity Inspector, and it seems things are fine there:

What would be an appropriate way to change this label's text either through IB or through the code. Also, I can't just change this label's text in Hint.xib, because I might to have multiple views on a screen that load (from) this xib and all of those views should have different text. I think I am missing something obvious here...Thanks for your hints :))

Answer 1

The problem is you have to load xib from bundle with "owner:self" so it should look like this:

class Hint:UIView {
    @IBOutlet var view: UIView!
    @IBOutlet weak var hintLabel: UILabel!
    private func setup(){

        Bundle.main.loadNibNamed("Hint", owner: self, options: nil)
        self.addSubview(view)
        view.frame = self.bounds
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        setup()
    }


    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()

        setup()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)

        setup()
    }
}

Also don't forget to set File Owner to Hint class in xib file (not UIView)

Answer 2

What you have is very close to working. The problem is you need to set the owner to the hint view, but you're trying to do that in a class method. self in a class method is the class, whereas you need self to be the instance of the class. Your fromNib method doesn't need to be a class method, it can be an instance method. Here's an example:

extension UIView {
    func createView<T : UIView>() -> T? {
        let type = type(of:self)
        guard
            let nibs = Bundle(for: type).loadNibNamed(String(describing: type), owner: self, options: nil),
            let nib = nibs.last
            else {
                return nil
        }

        return nib as? T
    }
}

Now in your view setup, you can use if let view = createView(){ //... } .