Stack Overflow Question: Is it possible to conditionally specify portrait or landscape mode?

gistfile1.txt

//
//  ViewController.swift
//  Browser
//
//  Created by Dan Beaulieu on 5/12/15.
//  Copyright (c) 2015 Dan Beaulieu. All rights reserved.
//

import UIKit
import WebKit

class ViewController: UIViewController, UITextFieldDelegate, WKNavigationDelegate {
    
    var webView: WKWebView
    var bounce : Bool = AppDelegate().userDefaults.valueForKey("Disable Bounce") as! Bool
    var scroll : Bool = AppDelegate().userDefaults.valueForKey("Disable Scroll") as! Bool
    var hideNavBar : Bool = AppDelegate().userDefaults.valueForKey("Hide Navigation Bar") as! Bool
    var storedUrl : String = AppDelegate().userDefaults.valueForKey("Web Address") as! String
    var statusBar : Bool = AppDelegate().userDefaults.valueForKey("Hide Status Bar") as! Bool
    var statusDefault : Bool = AppDelegate().userDefaults.valueForKey("Light Status Bar") as! Bool
    var portraitMode : Bool = AppDelegate().userDefaults.valueForKey("Portrait Mode") as! Bool
    var landscapeMode : Bool = AppDelegate().userDefaults.valueForKey("Landscape Mode") as! Bool
    
    
    @IBOutlet weak var barView: UIView!
    @IBOutlet weak var urlField: UITextField!
    @IBOutlet weak var backButton: UIBarButtonItem!
    @IBOutlet weak var progressView: UIProgressView!
    
    required init(coder aDecoder: NSCoder) {
        self.webView = WKWebView(frame: CGRectZero)
        super.init(coder: aDecoder)
        
        self.webView.navigationDelegate = self
    }

    override func viewWillAppear(animated: Bool) {
        if (hideNavBar == true) {
            barView.hidden = true
            urlField.hidden = true
            self.navigationController?.setNavigationBarHidden(true, animated: true)
            
        } else {
            barView.hidden = false
            urlField.hidden = false
            self.navigationController?.setNavigationBarHidden(false, animated: true)
        }
        self.navigationController?.setToolbarHidden(true, animated: true)
        
        // status bar settings
        
        if statusDefault == true {
            AppDelegate().setStatusBarStyleToLight()
        } else {
            AppDelegate().setStatusBarStyleToDefault()
        }
        
        if statusBar == true {
            AppDelegate().hideStatusBar()
        } else {
            AppDelegate().showStatusBar()
        }

    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        

        barView.frame = CGRect(x:0, y: 0, width: view.frame.width, height: 30)
    
        view.insertSubview(webView, belowSubview: progressView)
        
        webView.setTranslatesAutoresizingMaskIntoConstraints(false)
        let height = NSLayoutConstraint(item: webView, attribute: .Height, relatedBy: .Equal, toItem: view, attribute: .Height, multiplier: 1, constant: 0)
        let width = NSLayoutConstraint(item: webView, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .Width, multiplier: 1, constant: 0)
        view.addConstraints([height, width])
        
        webView.addObserver(self, forKeyPath: "loading", options: .New, context: nil)
        webView.addObserver(self, forKeyPath: "estimatedProgress", options: .New, context: nil)
        
        
        let url = NSURL(string:storedUrl)
        let request = NSURLRequest(URL:url!)
        webView.loadRequest(request)
        
        urlField.text = storedUrl
        
        evaluateScrollSettings()
        backButton.enabled = false
        
    }
    
    override func shouldAutorotate() -> Bool {
        
        if portraitMode == true || landscapeMode == true {
            return false
        } else {
            return true
        }
    }
    
    override func supportedInterfaceOrientations() -> Int {
        
        if portraitMode == true {
            return Int(UIInterfaceOrientationMask.Portrait.rawValue) | Int(UIInterfaceOrientationMask.PortraitUpsideDown.rawValue)
        } else {
            return Int(UIInterfaceOrientationMask.LandscapeLeft.rawValue) | Int(UIInterfaceOrientationMask.LandscapeRight.rawValue)
        }
    }
    

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        
    }
    
    override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
        
        barView.frame = CGRect(x:0, y: 0, width: size.width, height: 30)
    }
    
    func textFieldShouldReturn(textField: UITextField) -> Bool {
        urlField.resignFirstResponder()
        webView.loadRequest(NSURLRequest(URL:NSURL(string: urlField.text)!))
        
        return false
    }
    
    
    @IBAction func back(sender: UIBarButtonItem) {
        webView.goBack()
    }
    
    func evaluateScrollSettings() {
        if scroll == false {
            webView.scrollView.scrollEnabled = true
            
        } else {
            webView.scrollView.scrollEnabled = false
        }
        
        if bounce == false {
            webView.scrollView.bounces = true
            
        } else {
            webView.scrollView.bounces = false
        }

    }
    
    override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<()>) {
        if (keyPath == "loading") {
            backButton.enabled = webView.canGoBack
            //forwardButton.enabled = webView.canGoForward
        }
        if (keyPath == "estimatedProgress") {
            progressView.hidden = webView.estimatedProgress == 1
            progressView.setProgress(Float(webView.estimatedProgress), animated: true)
        }
    }
    
    func webView(webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: NSError) {
        let alert = UIAlertController(title: "Error", message: error.localizedDescription, preferredStyle: .Alert)
        alert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))
        presentViewController(alert, animated: true, completion: nil)
    }
    
    func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
        progressView.setProgress(0.0, animated: false)
    }

    override func prefersStatusBarHidden() -> Bool {
        
        return statusBar
        
    }
}