ios - Align label's center.x with image inside tabBar's imageView

Question

I need to get a label's center.x directly aligned with the image inside a tabBar's imageView. Using the below code the label is misaligned, instead of the label's text "123" being directly over the bell inside the tabBar, it's off to the right.

guard let keyWindow = UIApplication.shared.windows.first(where: { $0.isKeyWindow }) else { return }

guard let fourthTab = tabBarController?.tabBar.items?[3].value(forKey: "view") as? UIView else { return }

guard let imageView = fourthTab.subviews.compactMap({ $0 as? UIImageView }).first else { return }

guard let imageViewRectInWindow = imageView.superview?.superview?.convert(fourthTab.frame, to: keyWindow) else { return }

let imageRect = AVMakeRect(aspectRatio: imageView.image!.size, insideRect: imageViewRectInWindow)

myLabel.text = "123"
myLabel.textAlignment = .center // I also tried .left
myLabel.center.x = imageRect.midX
myLabel.center.y = UIScreen.main.bounds.height - 74
myLabel.frame.size.width = 50
myLabel.frame.size.height = 21

print("imageViewRectInWindow: (imageViewRectInWindow)") // (249.99999999403948, 688.0, 79.00000000298022, 48.0)
print("imageRect: (imageRect)") // (265.4999999955296, 688.0, 48.0, 48.0)
print("myLabelRect: (myLabel.frame)") // (289.4999999955296, 662.0, 50.0, 21.0)

question from:https://stackoverflow.com/questions/65845332/align-labels-center-x-with-image-inside-tabbars-imageview

Answer 1

It might be a layout issue, as in, setting the coordinates before everything is laid out. Where do you call the code from? I was able to get it to work with the following, but got strange results with some if the functions you use, so cut out a couple of them. Using the frame of the tabview worked for me, and calling the coordinate setting from the view controller's viewDidLayoutSubviews function.

class ViewController: UIViewController {

    var myLabel: UILabel = UILabel()

    var secondTab: UIView?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        self.view.addSubview(myLabel)
        myLabel.textColor = .black
        myLabel.text = "123"
        myLabel.textAlignment = .center // I also tried .left
        myLabel.frame.size.width = 50
        myLabel.frame.size.height = 21

        secondTab = tabBarController?.tabBar.items?[1].value(forKey: "view") as? UIView
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        guard let secondTab = secondTab else {
            return
        }

        myLabel.center.x = secondTab.frame.midX
        myLabel.center.y = UIScreen.main.bounds.height - 70
    }
}