- (void)restoreRootViewController:(UIViewController *)rootViewController
{
typedef void (^Animation)(void);
UIWindow* window = self.window;
rootViewController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
Animation animation = ^{
BOOL oldState = [UIView areAnimationsEnabled];
[UIView setAnimationsEnabled:NO];
window.rootViewController = rootViewController;
[UIView setAnimationsEnabled:oldState];
};
[UIView transitionWithView:window
duration:0.5f
options:UIViewAnimationOptionTransitionCrossDissolve
animations:animation
completion:nil];
}
iOS疯狂详解之 登陆后淡入淡出更换rootViewController
原文：http://blog.csdn.net/wanglongblog/article/details/44959609
