Working on furryfishApps’ new super secret project, I came across a strange problem, which not even stackoverflow had a solution for. At least I couldn’t find it.
When using the standard Apple template to create an iOS framework, Xcode creates, along with other stuff, a MainWindow.xib, which contains your UIWindow and is used to create your AppDelegate. Since its’ already hooked up to your Info.plist and works out of the box, I never bothered to question this construct - until today.
I noticed that our new App, when rotated has some weird effects at the bottom of the screen. It didn’t appear smooth, almost a little lagging. Since a picture tells more than my attempt to explain:
Since I’m using a pimped version of BCTabBarController, my first thought was that it must be the root of all evil. Fortunately, I was wrong! The sample coming with BCTabBarController doesn’t show those effects. I decided to set up a brand new projects with Apple view-based template. After integrating and setting up BCTabBarController, the same effects as in our App appeared. The projects were almost identical, so how could this be?
The only difference between the two projects was the setup of AppDelegate and its UIWindow. Apple’s template added a NSMainNibFile key and MainWindow.xib value to the Info.plist. Furthermore there’s an IBOutlet in the AppDelegate, which is hooked up to the UIWindow instance, configured in MainWindow.xib.
The BCTabBarController sample project on the other hand was configured “manually”. The UIWindow instance was created in the AppDelegate like this:
self.window = [[[UIWindow alloc] initWithFrame:
[[UIScreen mainScreen] bounds]] autorelease];
There was no MainWindow.xib, so no need for a corresponding key/value pair in the Info.plist. The AppDelegate is configured in the file main.m like this:
int retVal = UIApplicationMain(argc, argv, nil, @"EXAppDelegate");
After applying those changes to our new project, I was able to remove the weird effects and there’s a smooth autorotation experience now:
Honestly, I have no idea what the cause of this might be. Looking at the configuration of UIWindow instantiated by MainWindow.xib, there’s no difference to the one set up manually. I’m grateful for any clues, however, at the moment I’m just happy that I solved this issue.