presentViewController:animated:completion:要比presentModalViewController:好，
ios就推荐用前一个了
两个功能重复，后面的会没掉是肯定的
[[self presentingViewController] dismissModalViewControllerAnimated:YES];
[[selfpresentingViewController] dismissViewControllerAnimated:YEScompletion:nil];
//[[sharedDialog presentingViewController] dismissModalViewControllerAnimated:YES];
[[sharedDialogpresentingViewController] dismissViewControllerAnimated:YEScompletion:nil];
