如何在 Swift/iOS 中获取以编程方式添加的视图的宽度和高度？

Question

I have added a UIView and a UIImageView programatically, but I need its width and height. Is it possible to fetch it, if yes, please share how to fetch it.

Code:

let View1: UIView = {
            let viewView = UIView()
            viewView.translatesAutoresizingMaskIntoConstraints = false
            viewView.contentMode = .scaleAspectFit
            print(UserDefaults.standard.bool(forKey: "backgroundColourSelected"))
            if UserDefaults.standard.bool(forKey: "backgroundColourSelected") {
                viewView.backgroundColor = self.viewColor
            }else {
                viewView.backgroundColor = .white
            }
            viewView.clipsToBounds = true
            return viewView
        }()
    
        self.canvasView.addSubview(View1)
        
        View1.centerXAnchor.constraint(equalTo: canvasView.centerXAnchor, constant: 0).isActive = true
        View1.centerYAnchor.constraint(equalTo: canvasView.centerYAnchor, constant: 0).isActive = true
        View1.widthAnchor.constraint(equalTo: canvasView.widthAnchor, constant: 0).isActive = true
        View1.heightAnchor.constraint(equalTo: canvasView.widthAnchor, multiplier: aspectRatio).isActive = true

Answer 1

use override func viewWillLayoutSubviews() for ViewController and override func layoutSubviews() for UIView.

Example: - for UIViewControllers

override func viewWillLayoutSubviews() {
    print(yourView.frame.height)
}

for UIViews

override func layoutSubviews() {
    print(yourView.frame.height)
    print(yourView.frame.width)

}

Since your view is inside the function just move it out

class YourController / YourView {
private let imgView: UIImageView = {
    let iv = UIImageView()
    // do whatever you want with your image using iv. eg. iv.contentMode = .scaleAspectFit or iv.image = UIImage(named: "custom_img")
    return iv
}()

override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(imgView)
    //set constraints for your
}

// then use layoutSubViews(for views) / viewWillLayoutSubViews (for controller) and calculate the height

}

Answer 2

You need to know the life cycle of view controller.

To get height of any view use viewDidLayoutSubviews .

override func viewDidLayoutSubviews() {
      super.viewDidLayoutSubviews()

      print(view1.frame.size)
}

size property will print both final height and width.