Question

I know this is possible as Tapbots Pastebot does this. I am trying to grab the UIPasteboard when my iPhone app is running in the background and add it to a UITableView just as Pastebot does but I am also trying to shorten the link, if its a URL and copy that back to the UIPastboard so its ready for the user to paste anywhere. Now Pastebot apparently runs in the background by playing an audio file for 10 minutes. I have set up the NSNotificationCenter like so in the applicationDidFinishLaunching

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(pasteboardChangedNotification:) name:UIPasteboardChangedNotification object:[UIPasteboard generalPasteboard]];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(pasteboardChangedNotification:) name:UIPasteboardRemovedNotification object:[UIPasteboard generalPasteboard]];

- (void)pasteboardChangedNotification:(NSNotification*)notification {
pasteboardChangeCount_ = [UIPasteboard generalPasteboard].changeCount; 
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
     if (pasteboardChangeCount_ != [UIPasteboard generalPasteboard].changeCount) {
    [[NSNotificationCenter defaultCenter] postNotificationName:UIPasteboardChangedNotification object:[UIPasteboard generalPasteboard]];
     }
}

Can anyone point me in a direction on grabbing the UIPasteboard and shortening a link, if its a URL and sending it back to the UIPasteboard? I have read the multitasking dev documents and the UIPasteboard documents. If anyone has a solution can you please share them with me?

Thanks

Answer 1

The only way I have managed to achieve something similar is by not bothering with the NSNotificationCenter and instead just copying the contents of the UIPasteboard at regular intervals whilst in the background.

The code bellow checks the UIPasteboard once a second for a thousand seconds. I believe that an application can run in the background for around 10 minutes without playing audio. If you play an audio file in the background the application can keep running.

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Create a background task identifier
    __block UIBackgroundTaskIdentifier task; 
    task = [application beginBackgroundTaskWithExpirationHandler:^{
        NSLog(@"System terminated background task early"); 
        [application endBackgroundTask:task];
    }];

    // If the system refuses to allow the task return
    if (task == UIBackgroundTaskInvalid)
    {
        NSLog(@"System refuses to allow background task");
        return;
    }

    // Do the task
    dispatch_async(dispatch_get_global_queue(0, 0), ^{

        NSString *pastboardContents = nil;

        for (int i = 0; i < 1000; i++) 
        {
            if (![pastboardContents isEqualToString:[UIPasteboard generalPasteboard].string]) 
            {
                pastboardContents = [UIPasteboard generalPasteboard].string;
                NSLog(@"Pasteboard Contents: %@", pastboardContents);
            }

            // Wait some time before going to the beginning of the loop
            [NSThread sleepForTimeInterval:1];
        }

        // End the task
        [application endBackgroundTask:task];
    });


}