Triggering custom actions like open an URL with segues in storyboards is not quite obvious in the first attempt.
The trick is to drag a segue from the cell to the view controller icon on the bottom of the scene. This segue is pointing to the same scene as seen in the image below:

Now just set an identifier for the segue and trigger the correct action according to the identifier in the method -prepareForSegue
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:@"showDetail"]) {
// some other code
} else if ([[segue identifier] isEqualToString:@"openLink"]) {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://www.apple.com"]];
}
}
