Access UIView width at runtime

In Swift, how do I get the width (or height) at runtime, of a UIView that's created programmatically using auto layout constraints?

I've tried view1.frame.size.width and view1.frame.width, but both return 0.

I've been following an auto layout tutorial by MakeAppPie and added view1.layer.cornerRadius = view1.bounds.width/2 as below, but this had no effect, so I did a po on view1.bounds.width and got 0:

class ViewController: UIViewController {

func makeLayout() {

    //Make a view
    let view1 = UIView()
    view1.setTranslatesAutoresizingMaskIntoConstraints(false)
    view1.backgroundColor = UIColor.redColor()


    //Make a second view
    let view2 = UIView()
    view2.setTranslatesAutoresizingMaskIntoConstraints(false)
    view2.backgroundColor = UIColor(red: 0.75, green: 0.75, blue: 0.1, alpha: 1.0)

    //Add the views
    view.addSubview(view1)
    view.addSubview(view2)


    //--------------- constraints

    //make dictionary for views
    let viewsDictionary = ["view1":view1,"view2":view2]

    //sizing constraints
    //view1
    let view1_constraint_H:Array = NSLayoutConstraint.constraintsWithVisualFormat("H:[view1(>=50)]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)
    let view1_constraint_V:Array = NSLayoutConstraint.constraintsWithVisualFormat("V:[view1(50)]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)

    view1.addConstraints(view1_constraint_H)
    view1.addConstraints(view1_constraint_V)

    //view2
    let view2_constraint_H:NSArray = NSLayoutConstraint.constraintsWithVisualFormat("H:[view2(50)]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)
    let view2_constraint_V:NSArray = NSLayoutConstraint.constraintsWithVisualFormat("V:[view2(>=40)]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)

    view2.addConstraints(view2_constraint_H)
    view2.addConstraints(view2_constraint_V)

    //position constraints

    //views
    let view_constraint_H:NSArray = NSLayoutConstraint.constraintsWithVisualFormat("H:|-100-[view2]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)
    let view_constraint_V:NSArray = NSLayoutConstraint.constraintsWithVisualFormat("V:|-136-[view1]-100-[view2]-100-|", options: NSLayoutFormatOptions.AlignAllTrailing, metrics: nil, views: viewsDictionary)

    view.addConstraints(view_constraint_H)
    view.addConstraints(view_constraint_V)

    view1.layer.cornerRadius = view1.bounds.width/2

    }

override func viewDidLoad() {
    super.viewDidLoad()

    func supportedInterfaceOrientations() -> Int {
        return Int(UIInterfaceOrientationMask.All.rawValue)

    }

    // Do any additional setup after loading the view, typically from a nib.

    view.backgroundColor = UIColor(red: 0.9, green: 0.9, blue: 1, alpha: 1.0)
    makeLayout()

    }
}

回答1:

Add this and you are good to go:

override func viewDidLayoutSubviews() {
        println(self.view1.frame.size)
    }

you can look at width or height as you please.

回答2:

Just one thing about these fields:

self.view1.frame.size.width
self.view1.frame.size.height

Are only actual user device size if the view has been drawn to screen, else they are what ever you set them as in the storyboard. So if your trying to perform some kind of calculation before the view is drawn you will have to figure out the width or height another way!

回答3:

you can only use this

self.view1.frame.size.width
self.view1.frame.size.height