Hiding a label when phone is in landscape mode

问题:

I am creating an iPhone app which has icons with text labels underneath. I want the labels to be hidden when the phone is rotated to landscape mode, as there is not enough space for them. What is the easiest way to do this?

回答1:

You can first add an NSNotification to know orientation change on your device in viewDidLoad.

NSNotificationCenter.defaultCenter().addObserver(self, selector: "rotated", name: UIDeviceOrientationDidChangeNotification, object: nil)

This will call the function "rotated" when device know it's orientation changed, then you just have to create that function and put ur code inside.

func rotated()
{
    if(UIDeviceOrientationIsLandscape(UIDevice.currentDevice().orientation))
    {            
        print("landscape")
        label.hidden = true
    }

    if(UIDeviceOrientationIsPortrait(UIDevice.currentDevice().orientation))
    {
        print("Portrait")
        label.hidden = false
    }

}

Solution get from "IOS8 Swift: How to detect orientation change?"

回答2:

If you want to animate the change (e.g. fade out the label, or some other animation), you can actually do that in sync with the rotation by overriding the viewWillTransitionToSize method e.g.

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {

coordinator.animateAlongsideTransition({ (UIViewControllerTransitionCoordinatorContext) -> Void in

    let orient = UIApplication.sharedApplication().statusBarOrientation

    switch orient {
    case .Portrait:
        println("Portrait")
        // Show the label here...
    default:
        println("Anything But Portrait e.g. probably landscape")
        // Hide the label here...
    }

    }, completion: { (UIViewControllerTransitionCoordinatorContext) -> Void in
        println("rotation completed")
})

super.viewWillTransitionToSize(size, withTransitionCoordinator: coordinator)
}

Above code sample taken from the following answer: https://stackoverflow.com/a/28958796/994976

回答3:

Objective C Version

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)orientation  duration:(NSTimeInterval)duration
{
    if (UIInterfaceOrientationIsPortrait(orientation))
    {
        // Show the label here...
    }
    else
    {
       // Hide the label here...
    }
}

Swift Version

override func willAnimateRotationToInterfaceOrientation(toInterfaceOrientation: UIInterfaceOrientation, duration: NSTimeInterval) 
{
    if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation))
    {
        // Show the label here...
    }
    else
    {
        // Hide the label here...
    }
}