iOS9: Cannot open http link with Safari from 'openurl' method

Question

I cannot open the http link with Safari using 'openurl' method, if Safari is not opening in the background. But if Safari is running in background process, the app can open the http link with Safari successfully. I am not sure whether this is one of iOS9 changes.

Here is my code

    BOOL isAppInstalled = [[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString:[DELEGATE advertiseUrl]]];
        if(isAppInstalled) {
            [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://stackoverflow.com"]];
        }