It may be useful for others, I found a way to force the view to launch in landscape mode:

Put this in the viewDidLoad():

let value = UIInterfaceOrientation.landscapeLeft.rawValueUIDevice.current.setValue(value, forKey: "orientation")

and,

override var shouldAutorotate: Bool {    return true}

Swift 4

override func viewDidLoad() {    super.viewDidLoad()    let value = UIInterfaceOrientation.landscapeLeft.rawValue    UIDevice.current.setValue(value, forKey: "orientation")}override var supportedInterfaceOrientations: UIInterfaceOrientationMask {    return .landscapeLeft}override var shouldAutorotate: Bool {    return true}

If your view is embedded in a navigation controller, the above alone won't work. You have to cascade up by the following extension after the class definition.

extension UINavigationController {override open var shouldAutorotate: Bool {    get {        if let visibleVC = visibleViewController {            return visibleVC.shouldAutorotate        }        return super.shouldAutorotate    }}override open var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{    get {        if let visibleVC = visibleViewController {            return visibleVC.preferredInterfaceOrientationForPresentation        }        return super.preferredInterfaceOrientationForPresentation    }}override open var supportedInterfaceOrientations: UIInterfaceOrientationMask{    get {        if let visibleVC = visibleViewController {            return visibleVC.supportedInterfaceOrientations        }        return super.supportedInterfaceOrientations    }}}

Swift 3

override func viewDidLoad() {    super.viewDidLoad()    let value = UIInterfaceOrientation.landscapeLeft.rawValue    UIDevice.current.setValue(value, forKey: "orientation")}private func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {    return UIInterfaceOrientationMask.landscapeLeft}private func shouldAutorotate() -> Bool {    return true}

Swift 4 , Tested in iOS 11

You can specify the orientation in projectTarget -> General -> DeploymentInfo(Device Orientation) -> Portrait (Landscapeleft and Landscaperight are optional)

AppDelegate

    var myOrientation: UIInterfaceOrientationMask = .portrait    func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {        return myOrientation    }

LandScpaeViewController

override func viewDidLoad() {        super.viewDidLoad()        let appDelegate = UIApplication.shared.delegate as! AppDelegate        appDelegate.myOrientation = .landscape}

OnDismissButtonTap

let appDelegate = UIApplication.shared.delegate as! AppDelegate appDelegate.myOrientation = .portrait

Thats it. :)