IOS8-自动版式大小类更改通知/代理

Question

In my application I have a view that is different sizes in portrait and landscape. I need to have the backend controller code trigger a "redraw" of some graphical elements in this view when the phone changes. How do I do this? Is there some sort of delegate call to the UIView to know when its size has changed?

Answer 1

you can also write a custom like this:

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(orientationChanged:)
                                                 name:UIDeviceOrientationDidChangeNotification
                                               object:nil];
    // Do any additional setup after loading the view.
}

- (void)orientationChanged:(NSNotification *)notification
{
    //Redraw Here
}

Answer 2

All you need to do is implement following method in your custom controller:

override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {
    //do sth when rotated
}