Question

I’m aware that iOS has API’s to integrate iCloud for the apps.
Can I integrate iCloud in mac apps as well?
Will the implementation be different for Mac apps to integrate iCloud?
If Yes, are there any tutorials etc or reference websites?

Answer 1

Yes. iCloud is available on the Mac.
But Apple’s documentation for this topic still isn’t very complete. The only official resources I could find where the WWDC 2011 session 107 video and some notes in “What’s new in Mac OS X”

When Lion & iCloud still were under NDA I posted my findings in Apple’s devforums.
This is is an edited version of this post:

I am using a modified version of the WWDC 2011 Session 107 code. (transcribed from the video)
I had to remove the manual instantiation of NSFileCoordinator to get the sample working (the speaker mentions that the coordinator “might not be needed in the future”):

- (IBAction)moveToOrFromCloud:(id)sender
{
     NSFileManager* fm = [NSFileManager defaultManager];
     NSURL* fileURL = [[self document] fileURL];
     BOOL shouldMakeUbiquitous = [sender tag] == 1;
     NSURL* destinationURL;
     if(shouldMakeUbiquitous)
     {
          NSURL* rootURL = [fm URLForUbiquityContainerIdentifier:@"app.example"];
          NSURL* directoryURL = [rootURL URLByAppendingPathComponent:@"Documents"];
          [fm createDirectoryAtURL:directoryURL withIntermediateDirectories:NO attributes:nil error:NULL];
          destinationURL = [directoryURL URLByAppendingPathComponent:[fileURL lastPathComponent]];
     }
     else
     {
          destinationURL = [[[fm URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] objectAtIndex:0] URLByAppendingPathComponent:[fileURL lastPathComponent]];
     }
     NSError* error;
     if(![fm setUbiquitous:shouldMakeUbiquitous itemAtURL:fileURL destinationURL:destinationURL error:&error])
     {
          [[self document] presentError:error modalForWindow:[[self document] windowForSheet] delegate:nil didPresentSelector:NULL contextInfo:NULL];
     }
     else
     {
          [[self document] setFileURL:destinationURL];
          [[self document] setFileModificationDate:nil];
     }
}

The above IBAction is connected to a NSMenuItem that checks if the document is already in iCloud or if it needs to be uploaded:

- (BOOL)validateMenuItem:(NSMenuItem*)item 
{
     SEL action = [item action];
     if (action == @selector(moveToOrFromCloud:))
     {
          BOOL isUbiquitous = [[NSFileManager defaultManager] isUbiquitousItemAtURL:[[self document] fileURL]];
          [item setTitle:isUbiquitous ? @"Remove from Cloud": "Move to Cloud"];
          [item setTag:isUbiquitous?0:1];
          return [self.document fileURL] != nil;
     }    
     return YES;
}

Checklist for non-code tasks that are necessary to get iCloud document storage working:

• Check if iCloud support is activated in the Developer Certificate Utility
• Create a ubiquity container ID in the Developer Certificate Utility
• The Ubiquity container ID starts with your Team ID/Individual ID (see the account tab in member center)
• Enable Entitlements in Xcode
• Add your ubiquity container ID to the entitlements file (as described here “Requesting Entitlements for iCloud Storage.”)
• My plist Bundle ID had to match the ubiquity container ID (except for the Team ID)
• I was not able to add suffixes (e.g. “app.example.osx”, “app.example.ipad”, … as suggested in the doc above)
• Create a provisioning profile
• Make sure the profile is installed on your dev machine and shows up in Xcode & System Preferences
• Enable code signing in your apps build settings