视图切换的方式

1.用UINavigationController的时候用pushViewController:animated

前往： [self.navigationControllerpushViewController:webBrowseranimated:YES];

返回： [self.navigationControllerpopViewControllerAnimated:YES];

2. 其他时候用presentModalViewController:animated

前往：[self presentModalViewController:myviewControlleranimated:YES];

返回：[selfdismissViewControllerAnimated:YEScompletion:nil];