Only ONE VIEW landscape mode

SWIFT4

Add below code lines to your AppDelegate

var orientationLock = UIInterfaceOrientationMask.portrait
        
func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
  return self.orientationLock
}
        
struct AppUtility {
  static func lockOrientation(_ orientation: UIInterfaceOrientationMask) {
    if let delegate = UIApplication.shared.delegate as? AppDelegate {
      delegate.orientationLock = orientation
    }
  }
            
  static func lockOrientation(_ orientation: UIInterfaceOrientationMask, andRotateTo rotateOrientation:UIInterfaceOrientation) {
    self.lockOrientation(orientation)
    UIDevice.current.setValue(rotateOrientation.rawValue, forKey: "orientation")
  }
}

Add below code to the Controller you want to landscape

override func viewDidLoad() {
  super.viewDidLoad()
}
        
override func viewWillAppear(_ animated: Bool) {
  AppDelegate.AppUtility.lockOrientation(UIInterfaceOrientationMask.landscapeRight, andRotateTo: UIInterfaceOrientation.landscapeRight)
}
    
override func viewWillDisappear(_ animated : Bool) {
  super.viewWillDisappear(animated)
  AppDelegate.AppUtility.lockOrientation(UIInterfaceOrientationMask.portrait, andRotateTo: UIInterfaceOrientation.portrait)
}

Swift

AppDelegate.swift

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

Your landscape view controller

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.shouldRotate = true // or false to disable rotation

Objective-C

AppDelegate.h

@property (assign, nonatomic) BOOL shouldRotate;

AppDelegate.m

- (UIInterfaceOrientationMask)application:(UIApplication *)application
 supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    return self.shouldRotate ? UIInterfaceOrientationMaskAllButUpsideDown
                             : UIInterfaceOrientationMaskPortrait;
}

Your landscape view controller

AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
[appDelegate setShouldRotate:YES]; // or NO to disable rotation

I am gonna suppose you are targeting iOS 7 here (using XCode 5.1, I think I am right).

First, you have to understand that in order to open even just one view out of over 40 in landscape, your app should allow both landscape and portrait interface orientations. It is the case by default, but you can check it in your target's settings, General tab, Deployment Info section (see screenshot below).

Then, because you allowed both landscape and portrait for the entire app, you will have to tell every portrait-only UIViewController that it should not autorotate, adding this method's implementation:

- (BOOL)shouldAutorotate {
  return NO;
}

Finally, for your specific landscape-only controller, and because you said you are presenting it modally, you can just implement these methods:

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
  return UIInterfaceOrientationLandscapeLeft; // or Right of course
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
  return UIInterfaceOrientationMaskLandscape;
}

Hope this will help,