title: iCloud - UIDocument saveToUrl does not execute completion block
body: <p>I was testing with it the other day and it was working. Today, after calling this method, it never calls the completion block.</p>
  
  <p>Is there a case where the completion block is not called? I remember Apple said that it's always called regardless of what happened.</p>
  
  <p>Here's the code block:</p>
  
  <pre><code>dispatch_async (dispatch_get_global_queue (DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
              // Get ubiquitous url
              NSURL *ubiq = [[NSFileManager defaultManager]
                             URLForUbiquityContainerIdentifier:nil];
              NSURL *ubiquitousPackage = [[ubiq URLByAppendingPathComponent:
                                           @"Documents"] URLByAppendingPathComponent:fileName];
  
              // Create new CloudFile
              CloudFile *file = [[CloudFile alloc]initWithFileURL:ubiquitousPackage];
              file.data = data;
              [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onDocumentStateChanged:) name:UIDocumentStateChangedNotification object:file];             
  
              dispatch_async (dispatch_get_main_queue (), ^(void) {
                  [file saveToURL:file.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) {
                      NSLog(@"test");
                      if (success) {
                          [self sendEvent:ICLOUD_FILE_SAVE_SUCCESSFUL object:file];
                      } else {
                          [self sendEvent:ICLOUD_FILE_SAVE_FAILED];
                          NSLog(@"kaiCloud: Saving failed. (%@)",fileName);
                      }
  
                  }];
              });
  
          });
  </code></pre>
  
  <p>EDIT: Note that I added NSLog(@"test") and I'm not seeing it getting logged.</p>