Question

I’m using the following code to send a tweet through the Twitter.app:

NSPerformService(@"Tweet", [NSPasteboard generalPasteboard]);

How can i handle the following error, to display a custom message, if the user doesn’t have the twitter.app?

I’ve tried try catch but it’s not working.
Thanks

Answer 1

You try obtaining [NSApp servicesMenu] and searching it to see if a service by that name is present before invoking it.

---

Update with example:

NSUInteger itemIndex = [[[NSApp servicesMenu] itemArray] indexOfObjectPassingTest:^(id obj, NSUInteger idx, BOOL *stop){
    return [[(NSMenuItem*)obj title] isEqualToString:@"Tweet"];
}];
if (itemIndex != NSNotFound)
    NSPerformService(@"Tweet", [NSPasteboard generalPasteboard]);

---

Update 2:

The above was for the general case and has problems with localization and when the services menu gets updated. For a specific case of a service provided by a known app, you can check if the app is present using -[NSWorkspace absolutePathForAppBundleWithIdentifier:] to see if an app with a known bundle ID is present on the system.