What piece am I missing to set an iOS background? - iphone

Question

I have:
[A series of if statements sets backgroundImage to be something like [UIImageNamed #"Background-Default-Landscape"]; am I right to assume that the device will look for the file named Background-Default-Landscape#2x.png if it is a Retina display?]
UIImageView *backgroundView = [[UIImageView alloc] initWithImage:backgroundImage];
CGRect containerRect = CGRectZero;
containerRect.size = [backgroundImage size];
UIView *containerView = [[UIView alloc] initWithFrame:containerRect];
[containerView addSubview:backgroundView];
Right now my app is launching and once it loads displays a white screen, not a background specified (none of the backgrounds are solid white).
What am I missing to draw a background before I start putting things on the background, further below in the code?
Thanks,
--EDIT--
As far as code, I have:
- (void) renderScreen
{
int height = [[UIScreen mainScreen] bounds].size.height;
int width = [[UIScreen mainScreen] bounds].size.width;
UIImage *backgroundImage = nil;
if (height == 2048 || height == 2008 || height == 1024 || height == 1004 || height == 984)
{
backgroundImage = [UIImage imageNamed:#"Background-Default-Portrait"];
}
// Other such statements cut.
UIImageView *backgroundView = [[UIImageView alloc] initWithImage:backgroundImage];
CGRect containerRect = CGRectZero;
containerRect.size = [backgroundImage size];
UIView *containerView = [[UIView alloc] initWithFrame:containerRect];
[containerView addSubview:backgroundView];
[self.view addSubview:containerView];
Then below that are statements to draw on the background.
This method is called when the initial view loads and when it is rotated:
- (void)viewDidLoad
{
[super viewDidLoad];
[self renderScreen];
[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(renderScreen) name:UIDeviceOrientationDidChangeNotification object:nil];
}
The behavior is that the correct initial screen loads, then it fades to white and nothing interesting seems to happen after that.
--EDIT--
At the top, I have:
int height = [[UIScreen mainScreen] bounds].size.height;
int width = [[UIScreen mainScreen] bounds].size.width;
When I NSLog the height and width, for a retina device in landscape mode, I get a height of 1024 and a width of 768. The image displayed is a rotation of the portrait image; if I turn the device on the side the image neatly fills the whole screen but as-is the background displays a horizontally squeezed image.
Should I do anything different to be correctly obtaining height and width? I would expect for a device in landscape orientation the height would be 768 and the width would be 1024.

Answer 1

Every time renderScreen fires it will add two more subviews to the current controller's main view:
[containerView addSubview:backgroundView];
[self.view addSubview:containerView];
And this fires every time you rotate the device.
At least have the containerView as a property and replace it.
#property (nonatomic, strong) UIView *containerView;
and inside - (void) renderScreen
[self.containerView removeFromSuperview];
self.containerView = [[UIView alloc] initWithFrame:containerRect];
[self.view addSubview:self.containerView];
You could also add:
[self.view setNeedsDisplay];
So that the view is redrawn.