Question

I’m having difficulty figuring out how to deal with different device orientations for one screen of my iPad app. Here’s my situation:

~ All of this screen is rotating perfectly using springs and struts except for one label. The problem with this label is that I want it to move in an unorthodox manner (diagonally), thus springs and struts (or resizing masks will not work).

~ The way that I’m considering doing this is as such:

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)newInterfaceOrientation duration:(NSTimeInterval)duration
{
    if(UIInterfaceOrientationIsLandscape(newInterfaceOrientation))
    {
        self.myScreenLabel.frame = CGRectMake(600,0,400,100);
    }
    else {
        self.myScreenLabel.frame = CGRectMake(...//something); }
}

I would also put a check in viewDidLoad with similar logic. If in portrait mode, put label at... else put label at....

I think that this will work; however, I’m kinda wondering if there’s a better designed way to do this. The method above, has hard-coded numbers everywhere; thus, is there a better way to do this? Also, this method does not take advantage of the fact that I have my label positioned perfectly in the storyboard for portrait mode and it’s just landscape that I need to change.

Any suggestions on better design?

Answer 1

First question, I’ve implemented behavior on orientation change with your approach with no bad results, if you are okay that the method is triggered right before rotation happens. Alternatively, you can use NSNotifications to add a trigger on orientation change:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didRotate:)name:UIDeviceOrientationDidChangeNotification object:nil];

Then add a method like:

 - (void) didRotate:(NSNotification *)notification {   
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    if (orientation == UIDeviceOrientationLandscapeLeft) {
        //your code here
    }
 }

Regarding your second question, positioning frames like that is scary, but I think you realize that. Instead, position the element related to something else, just like a strut (which would say, always position the widget relative to a distance between it is strutted against). So use the window’s frame, the view’s frame, or some other UIView subclass in the view to position the object against, rather than absolute numbers.