How can I troubleshoot my custom URL scheme?

Question

I set up a simple event handler as mentioned here, but it appears that the selector isn't called. I put the code in my AppDelegate class and wired up the delegate in IB. Tried putting in some NSLog()s and breakpoints in the selector I expect to be called, but none of it is hit. The URL scheme works inasmuch as it launches my app, but it doesn't do anything after that. Can anyone advise how to troubleshoot this? Thanks!

Answer 1

The big question is: Where are you calling NSAppleEventManager's -setEventHandler:...? You need to call this before your app finishes launching if you want to catch a URL that started your app. If your app delegate is created in your MainMenu.nib, then either its -init or -awakeFromNib methods will work, but, for example, -applicationDidFinishLaunching: won't.

Also, make sure that the selector you provide to -setEventHandler: is exactly the same as your method name, paying particular attention to capitalization and the proper number of colons.

Obviously, if you posted your app delegate's relevant code, it would be quite helpful.

Answer 2

Thanks for the suggestions. I double-checked those things. I'm sure it's some newbie mistake, but I'd appreciate anyone looking at the code. (The URL bits are stored in info.plist.) Right now I'm just trying to confirm that it's working before I try to do anything with the URL.

- (void)init{
    self = [super init];
    if(self){
        [[NSAppleEventManager sharedAppleEventManager] setEventHandler:self andSelector:@selector(getUrl:withReplyEvent:) forEventClass:kInternetEventClass andEventID:kAEGetURL];
    }
}

- (void)getUrl:(NSAppleEventDescriptor *)event withReplyEvent:(NSAppleEventDescriptor *)replyEvent
{    
    NSString *url = [[event paramDescriptorForKeyword:keyDirectObject] stringValue];
    NSLog(url);
    // now you can create an NSURL and grab the necessary parts
}

Answer 3

Well, I can't help but notice that you're -init method is mis-declared. If should have return type id and have a return self; at the end.

- (id)init
{
    self = [super init];
    if (self) {
        [[NSAppleEventManager sharedAppleEventManager] setEventHandler:self andSelector:@selector(getUrl:withReplyEvent:) forEventClass:kInternetEventClass andEventID:kAEGetURL];
    }
    return self;
}

With those fixes, I was able to paste those two routines into a test AppController class and have it print out the URLs (with a custom scheme) that I typed into Safari. I'd put a breakpoint on that -init method and step through it to make absolutely sure that -setEventHandler: method is getting called.

Answer 4

Newbie mistake #2: Didn't set the class of my app delegate in IB. Fixing this and the init method as above got me going. Grrr...