present到最底层控制器
-(void)dismissToRootViewController
{
UIViewController*vc =self;
while(vc.presentingViewController) {
vc = vc.presentingViewController;
}
[vcdismissViewControllerAnimated:YEScompletion:nil];
}
连续dismissViewController两次
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];