Splash Screen

iPhone-only applications:
iPhone-only applications may only have one launch image. It should be in PNG format and measure 320 x 480 pixels. Name your launch image file Default.png.
For iPhone 4 high resolution, you can include an additional launch image. It should be in PNG formate and measure 640 x 960 pixels. Name it Default@2x.png. This image will get picked up by the iOS if your app is running on an iPhone 4.

Note: If your app is not running on an iPhone 4, and you provided both Default.png and Default@2x.png, iOS will automatically pick up Default.png as the launch image.

iPad-only applications:
Create a launch image for each supported orientation in the PNG format. Each launch image must be 1004 x 768 pixels (for landscape) or 748 x 1024 pixels (for portrait).
Default launch image files:

• Default-PortraitUpsideDown.png - upside-down portrait version.
• Default-LandscapeLeft.png - left-oriented landscape version.
• Default-LandscapeRight.png - right-oriented landscape version.
• Default-Portrait.png - generic portrait version.
• Default-Landscape.png - generic landscape version.
• Default.png - default portrait launch. Its usage is strongly discouraged, use more specific launch images instead.

Note: For iPad-only applications, it is common application to provide only Default-Portrait.png and Default-Landscape.png. More specific launch images will take precedence over the generic versions, for example Default-PortraitUpsideDown.png takes precedence over the Default-Portrait.png image file for this specific orientation. See the "Providing Launch Images for Different Orientations" section on the iPad Programming Guide for more information.

Universal applications:
Include launch images for both iPhone and iPad. iPhone launch image will still be named Default.png and Default@2x.png. Name your iPad portrait launch image Default-Portrait.png (do not use Default.png as the iPad portrait launch image).

1 down vote accepted

In order for viewWillAppear and viewDidAppear to function properly in a tab bar controller, you'll want to be sure to call those methods when you display the tab bar controller itself. That is, if you are creating your UITabBarController programmatically, be sure to call those methods: UITabBarController *myTabBarController = [[UITabBarController alloc] init]; [myTabBarController setViewControllers:myViewControllerArray]; [myTabBarController viewWillAppear:NO]; [[self view] addSubview:[myTabBarController view]]; [myTabBarController viewDidAppear:NO]; If your tab bar controller is being created in a NIB file, this doesn't apply - and in that case I'm not sure why your viewDidAppear method would not be called automatically.