Strange UI behaviour when app is opened with a URL Scheme

Question

The easiest way for me to explain this is to upload a test app, so I've stripped out everything that is unecessary and uploaded a bare bones project to SendSpace.

http://www.sendspace.com/file/z86g0z

I'm writing an app that will receive custom URL's from Mobile safari like "plasma://hello-world". These are then processed by my app and it displays a notification on screen.

In the test app the main class is a singleton and there is a "test" button this demonstrates what should happen when you open it via a URL. You get the custom link shown in a label on the screen and a green notification label at the top which then fades away. During this process the Xcode console shows this .....

2012-09-05 21:53:29.719 PlasmaLinker[2866:f803] Link: plasma:Test+Link
2012-09-05 21:53:29.778 PlasmaLinker[2866:f803] Show Alert: Success - Link Received
2012-09-05 21:53:35.779 PlasmaLinker[2866:f803] Remove Alert

All works fine.

Now I launch it from Mobile Safari by entering "plasma://hello-world" I hit enter and Safari switches to my app, the console shows EXACTLY the same output (with what ever URL you launch it with), however I get nothing in the UI at all. The link isn't placed in the text box, the notification is never shown.

What am I doing wrong? After its been launched with the URL you can again click the test button and see the UI elements change as desired. Its driving me nuts but I don't know enough to be able to get it to work when launched by a URL. Can someone please shed some light on this?

Kind Regards

Plasma

Answer 1

Your singleton method that gets the PlasmaLinker_ViewController is returning a different instance to the one that is created by the storyboard and added to the main window.

One example that works, (in your app delegate)

- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {

    NSString *link = [NSString stringWithFormat:@"%@",url];
    vc = (PlasmaLinker_ViewController*) self.window.rootViewController;
    [vc processLink:link];

    return YES;

}

Another option is to override the view controller's -(id)initWithCoder:(NSCoder *)decoder and set your shared instance to self in that method.

+ (PlasmaLinker_ViewController *) sharedInstance
{
    return _sharedInstance;
}

-(id)initWithCoder:(NSCoder *)decoder {

    NSLog(@"In initWithCoder!");
    if (!_sharedInstance) {
        if (self = [super initWithCoder:decoder]) {
            _sharedInstance = self;
        }
    }
    return _sharedInstance;
}