Getting the position of my UIBarButtonItem in iOS 11 - ios

Question

On App Start, I highlight one of my BarButtonItems. Since iOS11 I am not able to do this anymore because I need to initialise it on another way.
First my old ios 10 code. I saved my barButtonItemView after initialising it.
let item1 = UIBarButtonItem(image: UIImage(named: "iconProfile"), style: .plain, target: self, action: #selector(pushSettings))
self.navigationItem.setRightBarButtonItems([item1], animated: true)
if let view = self.navigationItem.rightBarButtonItem?.value(forKey: "view") as? UIView {
barButtonItemView = view
}
Now I was able to access the position of barButtonItem just by using the frame
barButtonItemView.frame.topMiddle.x
With ios 11 the picture on my UIBarButtonItem gets smaller. I was reading that I have to resize them by using constraints. So now I initialise my UIBarButtons by using this function:
let imageView = UIImageView(image: UIImage(named: imageName))
imageView.frame = CGRect(x: 5, y: 7, width: 20, height: 20)
let button = UIButton()
button.frame = CGRect(x: 0, y: 0, width: 30, height: 34)
button.addTarget(self, action: action, for: .touchUpInside)
button.widthAnchor.constraint(equalToConstant: 30).isActive = true
button.heightAnchor.constraint(equalToConstant: 34).isActive = true
button.addSubview(imageView)
let barItem = UIBarButtonItem(customView: button)
return barItem
I set my rightBarButtonItem on the same way and try to get the view on the same way.
self.navigationItem.setRightBarButtonItems([item1], animated: true)
if let view = self.navigationItem.rightBarButtonItem?.value(forKey: "view") as? UIView {
barButtonItemView = view
}
But this time my barButtonItemView has the x and y values set to 0,0. Has anyone an idea how I can get the position of my BarButtonItem depending on my screen?
What I tried
The first solution I tried is to call layoutIfNeeded() before I try to get the frame again. This is not working as well as the x and y values are still 0,0.

Answer 1

First, if your UIBarButtonItem only needs to display an UIImage, you should use [UIBarButtonItem initWithImage:style:target:action:] instead of customView for more standard layout. And if you want to custom the size of UIBarButtonItem, you can resize the image.
Second, before iOS 10, UIBarButtonItem's view was added in the UINavigationBar directly, but after iOS 11, UIBarButtonItem was added in a UIStackView, and the stackView was added in the UINavigationBar, so if you get a (0, 0) from the customView's frame.origin, it means that the customView is layout at the (0, 0) origin in the stackView.
Third, the view of the UIBarButtonItem would not be initialized until the UINavigationBar was shown and your UIBarButtonItem was put in the bar, so you can not get the view when the UIBarButtonItem just be initialized. Maybe you can try to get the view and its frame in your viewController's viewWillAppear: or viewDidAppear:.