Question

I’m working on a pretty simple multiview app for the iOS and I’ve been following a great tutorial in an Apress book. I’ve basically got my rootViewController instantiated and displayed with the app delegate, and I’ve got a number of content viewControllers (6) which I’d like to swap in and out based on user input. However, in the book they perform their switches with a button on a toolbar placed in the rootView using Interface Builder. It fires a method in rootView that loads up the new content ViewController and displays it.

My problem is that I’d like to perform the content view switch (that lies in my rootViewController instance), but I’d like to trigger the switch action with a button that’s in my content view (and is therefore unavailable as my File Owner is my contentViewController, whose reference is held inside my rootViewController).

Hopefully I’ve explained it well enough, please let me know if I should elaborate more. I appreciate any help!

Answer 1

You need to pass down a reference to your root view controller (RootViewController *rootViewController) when you create your content view either in a custom init method or by just assigning it after you created it: self.contentView.rootViewController = self;.

Now inside your content view you can then call the appropriate method in the root view controller to do the switch: [self.rootViewController switchView]. This call then can be triggered inside the method that is called when you press the button (IBAction method).

So this is what you need to do:
1) Create a property inside the your content view controller of type RootViewController

@class RootViewController;

@interface MyContentViewController : NSObject {
@private
    RootViewController *rootViewController;
}

@property (retain) RootViewController *rootViewController;

and make sure it retains the reference.
2) Synthesis the property and add the callback to the root view controller that switches the view:

@implementation MyContentViewController

@synthesize rootViewController;

- (IBAction) switchView:(id) sender {
    [rootViewController switchToNextView];
}

-(void) dealloc {
    [rootViewController release];
    [super dealloc];
}

Also release your retain reference at the end.

3) Assign the root view controller to the content view inside your RootViewController:

self.contentViewController = [[[MyContentViewController alloc]
                         initWithNibName:@"ContentView" 
                         bundle:nil] autorelease];
self.contentViewController.rootViewController = self;

That should be all. I hope that helps you.