How to use Auto Layout to stack views vertically in portrait mode and horizontally in landscape mode?

Question

I've got two views 'View A' and 'View B'. I'd like to display them side by side in landscape mode but one over the other in portrait mode. How can I achieve this using Auto Layout?

Answer 1

With the new UIStackView (introduced in iOS 9.0) it is now easily possible. Just add a UIStackView in the storyboard with your two views and define the desired proportion.

Then in the ViewController you can adapt the alignment of the axis directly on orientation change:

override func didRotateFromInterfaceOrientation(fromInterfaceOrientation: UIInterfaceOrientation) {
    switch UIDevice.currentDevice().orientation {
    case .Portrait:
        self.stackview.axis = .Vertical
    case .PortraitUpsideDown:
        self.stackview.axis = .Vertical
    case .LandscapeLeft:
        self.stackview.axis = .Horizontal
    case .LandscapeRight:
        self.stackview.axis = .Horizontal
    default:
        self.stackview.axis = .Vertical
    }
}