为什么我不能从不同的ViewController视图设置视图？

Question

@IBOutlet weak var containerView: UIView!

override func viewDidLoad() {
    super.viewDidLoad()

    let storyboard = UIStoryboard(name: "LinkDetail", bundle: nil)
    var vc : UIViewController = storyboard.instantiateViewControllerWithIdentifier("red") as UIViewController
    containerView = vc.view
    println(vc.view)
    }

I know I have the view controller id set in storyboard to be "red". And when I println the output is:

<UIView: 0x7fbdc1e5a820; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x7fbdc1e491b0>>

so the view must have been gotten correctly. So why can't I swap out my containerView UIView outlet with the view I get from code?

Answer 1

This is because you aren't holding a reference to the vc (red) view controller anywhere. The containerView is set to weak so nothing will retain the view that's being set on it.

I think you should be using Child View Controllers in this case.

Using your snippet, this is how you would add the View Controller as a child:

override func viewDidLoad() {
    super.viewDidLoad()

    let storyboard = UIStoryboard(name: "LinkDetail", bundle: nil)
    var vc : UIViewController = storyboard.instantiateViewControllerWithIdentifier("red") as UIViewController
    self.addChildViewController(vc)
    self.view.addSubview(vc.view)
    containerView = vc.view

    vc.didMoveToParentViewController(self)
}

Answer 2

// containerView = vc.view
containerView.addSuvview(vc.view)