Cannot create a custom view using Xib file due to nil subviews

user_2264888 0
Viewed 1366

I have a XIB file with 5 subviews. The XIB is set to a custom class like so

class Slide: UIView {

    @IBOutlet weak var descriptionImage: UIImageView!
    @IBOutlet weak var descriptionLabel: UILabel!
    @IBOutlet weak var hiLabel: UILabel!
    @IBOutlet weak var loLabel: UILabel!
    @IBOutlet weak var humidityLabel: UILabel!

}

I instantiate like so let slide = Slide()

When I try to set the variables ie slide.descriptionLabel = "Hello"

I get error

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

The stack trace shows that the XIB is instantiated, but the subviews are nil, and, therefore, cannot be set.

xib swift uiview
2 Answers

It's because you have to load the nib file ( here i suppose nib name is Slide )

let slide  = Bundle.main.loadNibNamed("Slide", owner: nil, options: nil)![0] as! Slide

as this 

let slide = Slide()

loads the view without it's layout so all attached views are nil

user_58200100

When you are dealing with custom views, using Xibs, you should load them first.

So, for example, in your Slide class you can create a static function like:

static func createView(with owner: Any) -> Slide {
    let nib = UINib.init(nibName: "YourNibName", bundle: nil)
    let views = nib.instantiate(withOwner: owner, options: nil)
    let view = views[0] as! Slide
    view.translatesAutoresizingMaskIntoConstraints = false
    return view
}

where YourNibName should be the name of your Xib file.

This static function can be used like:

let slide = Slide.createView(with: self)

// attach the view to a superview
aSuperview.addSubview(slide)

// setup the right constraints
// for example
slide.topAnchor.constraint(equalTo: aSuperview.topAnchor).isActive = true
// ...and so on

The important bit is then to set in Interface Builder the right view for your Xib:

enter image description here

To recap your view should look like (note that I renamed Slide to SlideView. It sounds better to me):

class SlideView: UIView {
    @IBOutlet var descriptionImage: UIImageView!
    @IBOutlet var descriptionLabel: UILabel!
    @IBOutlet var hiLabel: UILabel!
    @IBOutlet var loLabel: UILabel!
    @IBOutlet var humidityLabel: UILabel!

    static func createView(with owner: Any) -> SlideView {
        let nib = UINib.init(nibName: "YourNibName", bundle: nil)
        let views = nib.instantiate(withOwner: owner, options: nil)
        let view = views[0] as! SlideView
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }
}
user_2316840
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