IBOutlet properties nil after custom view loaded from xib - ios

Question

Something strange going on with IBOutlets.
In code I've try to access to this properties, but they are nil. Code:
class CustomKeyboard: UIView {
#IBOutlet var aButt: UIButton!
#IBOutlet var oButt: UIButton!
class func keyboard() -> UIView {
let nib = UINib(nibName: "CustomKeyboard", bundle: nil)
return nib.instantiateWithOwner(self, options: nil).first as UIView
}
override init() {
super.init()
commonInit()
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
// MARK: - Private
private func commonInit() {
println(aButt)
// aButt is nil
aButt = self.viewWithTag(1) as UIButton
println(aButt)
// aButt is not nil
}
}

Answer 1

That's expected, because the IBOutlet(s) are not assigned by the time the initializer is called.
Instead of calling commonInit() in init(coder:), do that in an override of awakeFromNib as follows:
// ...
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
commonInit()
}
// ...

Answer 2

Assuming you tried the standard troubleshooting steps for connecting IBOutlets, try this:
Apparently, you need to disable awake from nib in certain runtime cases.
override func awakeAfter(using aDecoder: NSCoder) -> Any? {
guard subviews.isEmpty else { return self }
return Bundle.main.loadNibNamed("MainNavbar", owner: nil, options: nil)?.first
}

Answer 3

Your nib may not be connected. My solution is quite simple. Somewhere in your project (I create a class called UIViewExtension.swift), add an extension of UIView with this handy connectNibUI method.
extension UIView {
func connectNibUI() {
let nib = UINib(nibName: String(describing: type(of: self)), bundle: nil).instantiate(withOwner: self, options: nil)
let nibView = nib.first as! UIView
nibView.translatesAutoresizingMaskIntoConstraints = false
self.addSubview(nibView)
//I am using SnapKit cocoapod for this method, to update constraints. You can use NSLayoutConstraints if you prefer.
nibView.snp.makeConstraints { (make) -> Void in
make.edges.equalTo(self)
}
}
}
Now you can call this method on any view, in your init method, do this:
override init(frame: CGRect) {
super.init(frame: frame)
connectNibUI()
}

Answer 4

Building on #ScottyBlades, I made this subclass:
class UIViewXib: UIView {
// I'm finding this necessary when I name a Xib-based UIView in IB. Otherwise, the IBOutlets are not loaded in awakeFromNib.
override func awakeAfter(using aDecoder: NSCoder) -> Any? {
guard subviews.isEmpty else { return self }
return Bundle.main.loadNibNamed(typeName(self), owner: nil, options: nil)?.first
}
}
func typeName(_ some: Any) -> String {
return (some is Any.Type) ? "\(some)" : "\(type(of: some))"
}

Answer 5

There is possibility that you not mentioned the FileOwner for xib.
Mention its class in File owner not in views Identity Inspector .

Answer 6

And how did you initiate your view from the controlller? Like this:
var view = CustomKeyboard.keyboard()
self.view.addSubview(view)