Question

I’ve set up a delegate methos to communicate from my masterViewController to my detailViewController but the delegate method isn’t getting called.

MasterViewController.h

#import <UIKit/UIKit.h>

@class DetailViewController;
@class MasterViewController;

@protocol MasterViewControllerDelegate
- (void)SelectionChanged:(NSString *)url;
@end

@interface MasterViewController : UITableViewController

@property (nonatomic, weak) id<MasterViewControllerDelegate> delegate;
@property (strong, nonatomic) DetailViewController *detailViewController;

@end

Then in my MasterViewController.m I’m synthesizing the delegate:

@synthesize delegate;

And finally I’m calling the delegate method from my didSelectRowAtIndexPath method like so:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSArray *links = [NSArray arrayWithObjects:
                      @"http://www.link1.com",
                      @"http://www.link2.com",
                      @"http://www.link3.com",
                      nil];

   [self.delegate SelectionChanged:[links objectAtIndex: indexPath.row]];
}

Then in my DetailViewController.h I have:

@interface DetailViewController : UIViewController <UISplitViewControllerDelegate, MasterViewControllerDelegate>

And in DetailViewController.m:

- (void)SelectionChanged:(NSString *)url {
    NSLog(@"URL is %@", url);
}

When I run the app, the NSLog from SelectionChanged is never called and I get no errors. Any ideas?

Answer 1

Okay I figured it out… In my AppDelegate.m file I added the following to didFinishLaunchingWithOptions

DetailViewController *detail = (DetailViewController *)navigationController.topViewController;
UINavigationController *masterNavigationController = [splitViewController.viewControllers objectAtIndex:0];
MasterViewController *master = (MasterViewController *)masterNavigationController.topViewController;

NSLog(@"%@",masterNavigationController.topViewController);
master.delegate = detail;

So the whole method looks like this:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController;
    UINavigationController *navigationController = [splitViewController.viewControllers lastObject];
    splitViewController.delegate = (id)navigationController.topViewController;

    DetailViewController *detail = (DetailViewController *)navigationController.topViewController;
    UINavigationController *masterNavigationController = [splitViewController.viewControllers objectAtIndex:0];
    MasterViewController *master = (MasterViewController *)masterNavigationController.topViewController;

    NSLog(@"%@",masterNavigationController.topViewController);
    master.delegate = detail;

    return YES;
}

Basically the problem is that I wasn’t assigning the delegate anywhere…. duh.