setSelectedIndex via delegate method - ios

Question

I'm trying to call the setSelectedIndex of my tabBarViewController via a delegate method in another viewController.
I've got the whole delegate part working, and the method call in my tabBarViewController correctly Logs to the console as being called.
The problem I'm having is, that it doesn't change my tabBar to the correct index. This is the method being called in my tabBarViewController.m
-(void)passNewSelectedIndex{
NSLog(#"delegate method called"); //This correctly outputs to the logs when the delegate method is called.
[self setSelectedIndex:1];
}
But it doesn't work.
Now, if I call [self setSelectedIndex:1]; in my viewDidLoad of the tabBarViewController.m, it works, and it correctly displays the tab at index:1. But that's obviously not where I want to set it. I think I might be missing something really obvious, but I just cant figure out what.
EDIT Posted the code for the concerned .h's and .m's
ScoreViewController.h:
#protocol ScoreViewControllerDelegate <NSObject>
- (void)passNewSelectedIndex;
#end
#interface CEWSoreViewController : UICollectionViewController{
id <ScoreViewControllerDelegate> scoreDelegate;
}
#property (nonatomic, weak) id<ScoreViewControllerDelegate> scoreDelegate;
#end
ScoreViewController.m:
- (void)passNewSelectedIndex{
CEWTabBarViewController *instanceOfTabBarCont = [[CEWTabBarViewController alloc] init];
self.scoreDelegate = instanceOfTabBarCont;
NSLog(#"I was called, hurray");
[instanceOfTabBarCont passNewSelectedIndex];
}
TabBarViewController.h
#import "CEWFinalScoreViewController.h"
#interface CEWTabBarViewController : UITabBarController <UITabBarControllerDelegate, ScoreViewControllerDelegate>{
}
#end
tabBarViewController.m:
-(void)passNewSelectedIndex{
NSLog(#"delegate method called");
NSLog(#"self.tabBar: %#", self.tabBar);
[self setSelectedIndex:1];
}
AppDelegate.m
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.window.backgroundColor = [UIColor whiteColor];
CEWTabBarViewController *tabViewController = [[CEWTabBarViewController alloc] init];
self.window.rootViewController = tabViewController;
[self.window makeKeyAndVisible];
return YES;
Hope this makes a bit more sense now.

Answer 1

The problem is exactly as I expected:
- (void)passNewSelectedIndex{
CEWTabBarViewController *instanceOfTabBarCont = [[CEWTabBarViewController alloc] init];
self.scoreDelegate = instanceOfTabBarCont;
NSLog(#"I was called, hurray");
[instanceOfTabBarCont passNewSelectedIndex];
}
You're instantiating a new tab bar controller and calling the passNewSelectedIndex method on that. The problem is, that tab bar controller isn't the one controlling the tab bar your view controllers are in.
Try this:
[(CEWTabBarViewController*)self.tabBarController passNewSelectedIndex];
Depending on your navigational setup, you may need this instead:
[(CEWTabBarViewController*)self.view.window.rootViewController passNewSelectedIndex];
We would need a LOT more of your project to figure out exactly the best way to get a reference to the right Tab Bar Controller (I'm not recommending you do this), but the point is, we have to get a reference to the already instantiated tab bar controller that is already controlling our tab bar, not simply instantiate a new one and expect it to magically control our current tab bar.
The reason it works in viewDidLoad of your tab bar controller is because every instance of your tab bar controller calls viewDidLoad on its own. When moved into passNewSelectedIndex, this method is only called when someone else calls it.

Answer 2

selectedIndex is a property of UITabBarController
[self setSelectedIndex:1];
This would work only if the current controller is a subclass of UITabBarController.
For your scenario, you would have to pass the UITabBarController as a parameter
-(void)passNewSelectedIndex:(UITabBarController *)tabBar {
NSLog(#"delegate method called");
[tabBar setSelectedIndex:1];
}
If the view controller which declares your delegate method is itself a subclass of UITabBarController, then the [self setSelectedIndex:1];
would result in calling its own tabBar and not the one on which the delegate method is set.