NSOpenPanel in Swift . How to open?

I have this Objective-C Code :

- (IBAction)selectFileButtonAction:(id)sender {

    //create open panel...
    NSOpenPanel* openPanel = [NSOpenPanel openPanel];
    // NSLog(@"Open Panel");
    //set restrictions / allowances...
    [openPanel setAllowsMultipleSelection: NO];
    [openPanel setCanChooseDirectories:NO];
    [openPanel setCanCreateDirectories:NO];
    [openPanel setCanChooseFiles:YES];
    //only allow images...
    [openPanel setAllowedFileTypes:[NSImage imageFileTypes]];
    //open panel as sheet on main window...
    [openPanel beginWithCompletionHandler:^(NSInteger result)  {
        if (result == NSFileHandlingPanelOKButton) {

            //get url (should only be one due to restrictions)...
            for( NSURL* URL in [openPanel URLs] ) {
               // self.roundClockView1.URL = URL ;
                _thePath = URL;
                currentSelectedFileName = [[URL path] lastPathComponent];
               // [_roundClockView1 setNeedsDisplay:1];
                [self openEditor];
            }

        }
    }];

Now I want to write this the same thing in swift. Here is what I've done until now :

@IBAction func selectAnImageFromFile(sender: AnyObject) {
    var openPanel = NSOpenPanel()
    openPanel.allowsMultipleSelection = false
    openPanel.canChooseDirectories = false
    openPanel.canCreateDirectories = false
    openPanel.canChooseFiles = true
    openPanel.beginWithCompletionHandler(handler: (Int) -> Void)
}

and here I'm stuck. Thanks for help.

@IBAction func selectAnImageFromFile(sender: AnyObject) {
    let openPanel = NSOpenPanel()
    openPanel.allowsMultipleSelection = false
    openPanel.canChooseDirectories = false
    openPanel.canCreateDirectories = false
    openPanel.canChooseFiles = true
    openPanel.beginWithCompletionHandler { (result) -> Void in
        if result == NSFileHandlingPanelOKButton {
            //Do what you will
            //If there's only one URL, surely 'openPanel.URL'
            //but otherwise a for loop works
        }
    }
}

I'm guessing you got stuck on the completion handler part? In any case, handling the URL from the open panel should be ok from there, but comment if you want me to add more. :)