1.异步执行导航栏控制器回退回跟页面，以下vc为当前控制器
dispatch_async(dispatch_get_main_queue(), ^{
[vc.navigationController popToRootViewControllerAnimated:NO];
});
2.分栏切换显示页
AppDelegate *delegate = (AppDelegate *)[UIApplication sharedApplication].delegate；
UITabBarController *tabbarCtr = (UITabBarController *)delegate.window.rootViewController;
[tabbarCtr setSelectedIndex:index];
