From: http://www.cnblogs.com/think/archive/2011/05/03/ForceViewRotateImmediatly.html
在现在的ios sdk中，我们一般通过UIApplication的setStatusBarOrientation:来进行View的强制旋转（当然，还要配合- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation），但是，setStatusBarOrientation并不一定马上会执行shouldAutorotateToInterfaceOrientation进行界面旋转，这时，有个小技巧可以让界面马上旋转过来，那就是调用一下 UINavigationController的presentModalViewController:animated:
.........{
//为了马上旋转过来
UINavigationController* nav = [[GurgleAppDelegate getAppDelegate] navigationController];
UIViewController *controller = [[UIViewController alloc] init];
UINavigationController *parentController = [[UINavigationController alloc] initWithRootViewController:controller];
[nav presentModalViewController:parentController animated:NO];
[controller dismissModalViewControllerAnimated:NO];
[parentController release];
[controller release];
}
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations.
return viewOrientation == interfaceOrientation;
}