usable view size after status bar and navigation bar - ios

Question

I am writing an iPad app that needs to know the usable area of the view for drawing purposes. The view is added into a Navigation controller, so I have the status bar plus the navigation controller both taking up a certain number of pixels. My app happens to be in landscape mode, although I don't think that's relevant.
I am able to get the correct view size AFTER rotation using didRotateFromInterfaceOrientation. But I can't figure out how to do it without the screen being rotated.
- (void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
[self.view setFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
NSLog(#"drfi %d %d", (int)self.view.frame.size.width, (int)self.view.frame.size.height);
}
^^ that works after rotation. Not before. Can't figure out how to get accurate numbers. And I REALLY don't want to hard wire this.
I will also need this function to be device independent -- it should work on the NEW iPad as well as the older iPad resolutions. I can handle the scaling issues once I know the exact usable area. Why is this so hard? Help!!

Answer 1

I don't think you need to specify your frame's view within the didRotateFromInterfaceOrientation what i will suggest instead is setting some properties to your view autoresizing mask so that it automatically resize itself according to your view orientation.
By setting this for example to your view when your view is loaded (viewDidLoad method):
self.view.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
you specify that your view will change its width and height automatically and can get the right values you need to get from there.
You should read this: http://developer.apple.com/library/ios/#documentation/WindowsViews/Conceptual/ViewPG_iPhoneOS/CreatingViews/CreatingViews.html#//apple_ref/doc/uid/TP40009503-CH5-SW1
for a better understanding of views in iOS
EDIT
Also you probably want to spot what is the orientation of your device which can be accomplish with [[UIApplication sharedApplication] statusBarOrientation];

Answer 2

Your application looks like: there is a start up view, then in this view you will load and add a main view into window, right? Then you should do as below in your main view:
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
CGRect frame = self.view.frame;
frame.origin.y = frame.origin.y + 20.0;
self.view.frame = frame;
}
return self;
}

Answer 3

Try this.
CGRect frame = [UIScreen mainScreen].bounds;
CGRect navFrame = [[self.navigationController navigationBar] frame];
/* navFrame.origin.y is the status bar's height and navFrame.size.height is navigation bar's height.
So you can get usable view frame like this */
frame.size.height -= navFrame.origin.y + navFrame.size.height;

Answer 4

You can get this dynamically by combining an instance method with a category method:
Instance method:
This assumes that your view controller (self) is embedded within a navigation controller.
-(int)getUsableFrameHeight {
// get the current frame height not including the navigationBar or statusBar
return [MenuViewController screenHeight] - [self.navigationController navigationBar].frame.size.height;
}
Class category method:
+(CGFloat)screenHeight {
CGFloat screenHeight;
// it is important to do this after presentModalViewController:animated:
if ([[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortrait ||
[[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortraitUpsideDown){
screenHeight = [UIScreen mainScreen].applicationFrame.size.height;
} else {
screenHeight = [UIScreen mainScreen].applicationFrame.size.width;
}
return screenHeight;
}
The above will consistently give you the usable frame height after the status bar and navigation bar have been removed, in both portrait and landscape.
Note: the class method will automatically deduct the 20 pt for the status bar - then we just subtract the navigation header variable height (32 pt for landscape, 44 pt for portrait).