title: How do I programmatically change system-wide desktop picture?
body: <p>I'm using the following code to set desktop picture:</p>
  
  <pre><code>NSURL* newImage = [[NSURL alloc] initFileURLWithPath:@"/Users/name/Pictures/test.png"];
  [[NSWorkspace sharedWorkspace] setDesktopImageURL:newImage forScreen:screen options:nil error:&amp;nserror];
  </code></pre>
  
  <p>It works fine and the desktop picture changed as I required. But it does not change the system-wide desktop preferences (for example, change picture every 30 minutes). How can I change the system-wide desktop preferences?</p>