首先确认你的工程级别 支持横屏

然后在你的UIViewController中：

override func shouldAutorotate() -> Bool {
    return false
}
    
override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
    return UIInterfaceOrientationMask.LandscapeLeft
}
    
override func preferredInterfaceOrientationForPresentation() -> UIInterfaceOrientation {
    return UIInterfaceOrientation.LandscapeLeft
}

在启动这个UIViewController中，注意一定要present，不要push，这是个关键

[self.navigationController presentViewController:controller animated:YES completion:nil];

更多可以参考：http://stackoverflow.com/questions/17063020/how-to-load-a-uiviewcontroller-in-landscape-mode-if-its-parent-is-in-portrait-mo