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iosautolayoutconstraintsframe

Does self.view has constraints?

self.view is on the ViewController. Does it have any constraints? I found it had a top and a left constraint. It has a frame for sure. The autolayout system starts from self.view. I mean until self.view the iOS system is still using frame for positioning the views. After that, our views are able to be added with autolayout. So in the viewcontroller, I use self.frame.size.width for the width constraint for my own view is the correct approach to do? Am I right?

Solution

  • Use SCREEN_WIDTH and It's very easy to get your device size and manage your own view properly:

    let SCREEN_WIDTH : CGFloat = UIScreen.main.bounds.width
let SCREEN_HEIGHT : CGFloat = UIScreen.main.bounds.height

    For more information you can refer this : link

    Example : You should add your own new view programatically.

    import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    let SCREEN_WIDTH : CGFloat = UIScreen.main.bounds.width
    let SCREEN_HEIGHT : CGFloat = UIScreen.main.bounds.height

    let newView = UIView()
    newView.translatesAutoresizingMaskIntoConstraints = false
    newView.backgroundColor = UIColor.black

    newView.frame.size = CGSize(width: SCREEN_WIDTH * 0.5 , height: SCREEN_HEIGHT * 0.5)

    self.view.addSubview(newView)
    self.view.layoutIfNeeded()
  }
}

    Here I am giving the frame to the constraints of my customized view. I don't want to give this value in a format of frame.size. I want to use somethings like constraint.constant. I mean pure autolayout. image