从AppDelegate和Tab Bar推送View Controller

Question

My app is setup with a Tab Bar Controller as the RootViewController , and each Tab has a NavigationController in it. When certain actions are performed, I want the app to push a ViewController onto the screen. The flow of this is that when the app starts, or opens from background, it checks a stored NSDate and compares it to the current date. If the right condition is met, it shows a UIAlertView . If the button I named "Push" is selected, it runs the code to push the new view. This is the reason I need it to be ran from the AppDelegate , as there is no guarantee what tab may be open if the app is being used in the background. Since every tab contains a NavigationController , I thought I could run this from the AppDelegate:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

      if (alertView.tag == 100) {
         if (buttonIndex == 0) {
              //Cancel
              NSLog(@"Cancel");
          }
         if (buttonIndex == 1) {
              NSLog(@"OK");
              [self.tabBarController.selectedViewController pushViewController:self.newView animated:YES];
         }
     }
}

I get a warning message that says UIViewController may not respond to -pushViewController:animated . Any suggestions as to what else I could do?

Answer 1

The return type for selectedViewController is UIViewController, so you need to tell the compiler that it's actually a navigation controller. You do that with a cast,

[(UINavigationController *)self.tabBarController.selectedViewController pushViewController:self.newView animated:YES];

Answer 2

Try this!!

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

if (buttonIndex == 0) {
    NSLog(@"Cancel");
}else{
    NSLog(@"Push");
    [self loadTabbar];
} 
}

-(void)loadTabbar{
UITabBarController *tabbarController = [[UITabBarController alloc]init];
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];

ViewControllerOne *tab1 = [storyboard instantiateViewControllerWithIdentifier:@"ViewControllerOne"];
UINavigationController *navi1 = [[UINavigationController alloc]initWithRootViewController:tab1];
tab1.tabBarItem.title = @"Tab1";
tab1.tabBarItem.image = [UIImage imageNamed:@"1.png"];

ViewControllerTwo *tab2 = [storyboard instantiateViewControllerWithIdentifier:@"ViewControllerTwo"];
UINavigationController *navi2 = [[UINavigationController alloc]initWithRootViewController:tab2];
tab2.tabBarItem.title = @"Tab2";
tab2.tabBarItem.image = [UIImage imageNamed:@"2.png"];

NSArray *tabArrays = [[NSArray alloc]initWithObjects:navi1,navi2, nil];

tabbarController.viewControllers = tabArrays;
tabbarController.tabBar.selectionIndicatorImage = [UIImage imageNamed:@"tabbar_selected.png"];

[self.window setRootViewController:tabbarController];
[self.window makeKeyAndVisible];
}

Comment here if this is the one you are looking forward!!