使用情节提要板时，使用UITabBarController在视图之间传递数据

Question

I've been converting an application to use storyboards. I'm sure this is a simple problem, but somehow I can't seem to figure out the 'correct' way of doing it, coming as we are from the old XIB world.

One of the subsections of it contains a UITabBarController, each with some subviews within it.

The action that launches this set of tabs works perfectly; I detect the segue, and set some data properties within my (custom) UITabBarController.

Next, I would like to be able to pass that data to the child views when they get created. But - because these tabs are simply 'relationships' and not segue's, I can't do what I do everywhere else, which is override the 'prepareForSegue' function.

In the old XIB universe, I'd simply bind some IBOutlets together between the tab controller and the child views. But I can't do that in storyboards, because the parent and children are separate 'scenes'.

I've tried making my UITabBarController class implement its own delegate, override 'didSelectViewController' and doing 'self.delegate = self' which almost works, except for the fact that it is never called with the first tab when the view is initially shown.

What's the "correct" (or 'best') way to do this? Please don't tell me to get/set some value on the app delegate, as this is 'global variable' territory - nasty.

Answer 1

Try looping through the view controllers on the UITabBarController, eg in this example the setData method is called from the segue in to the UITabBarController, and it then loops through the child view controllers, making a similar call on the child controller to set the data on that too;

- (void)setData:(MyDataClass *)newData
{
    if (_myData != newData) {
        _myData = newData;

        // Update the view.
        [self configureView];
    }

}

- (void) configureView {
       for (UIViewController *v in self.viewControllers)
       {
           if ([v isKindOfClass:[MyDetailViewController class]])
           {
               MyDetailViewController *myViewController = v;
                    [myViewController setData:myData];
           }
       }
 }