WKWebView added as Subview is not resized on rotation in Swift

Question

I'm working on adding a new reading view to my browser app. It is another view controller, that only includes a WKWebView added as a subview with a button (and gesture) to close the view. Everything works great, but when I rotate the device, the subview isn't resized, so I have one half of the screen empty.

The WKWebView in the Reading View gets the URL of the main View Controller with a segue performed after the user taps a button on the main View Controller and that URL is stored as webpageURL.

Here is the code I used:

import UIKit
import WebKit

class ReadingViewController: UIViewController, UIGestureRecognizerDelegate, WKNavigationDelegate, WKScriptMessageHandler {

@IBOutlet weak var _closeButton: UIButton!
@IBOutlet weak var _progressView: UIProgressView!
@IBOutlet weak var _loadingErrorView: UIView!

var webpageURL: NSURL?

var _webView: WKWebView?
var _isMainFrameNavigationAction: Bool?
var _loadingTimer: NSTimer?

var _swipeFromTopRecognizer: UIScreenEdgePanGestureRecognizer?
var _panFromRightRecognizer: UIScreenEdgePanGestureRecognizer?
var _panFromLeftRecognizer: UIScreenEdgePanGestureRecognizer?
var _errorView: UIView?
var _isCurrentPageLoaded = false

var _progressTimer: NSTimer?
var _isWebViewLoading = false


override func viewDidLoad() {
    super.viewDidLoad()

    var contentController = WKUserContentController();
    var scaleToFit = WKUserScript(source: "var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);", injectionTime: WKUserScriptInjectionTime.AtDocumentStart, forMainFrameOnly: true)
    contentController.addUserScript(scaleToFit)
    contentController.addScriptMessageHandler(self, name: "callbackHandler")

    var webViewConfiguration: WKWebViewConfiguration = WKWebViewConfiguration()
    webViewConfiguration.allowsInlineMediaPlayback = true
    webViewConfiguration.mediaPlaybackRequiresUserAction = false

    _webView = WKWebView(frame: self.view.frame, configuration: webViewConfiguration)

    self.view.addSubview(_webView!)
    _webView!.navigationDelegate = self
    self.view.sendSubviewToBack(_webView!)
    _webView!.allowsBackForwardNavigationGestures = true

    _loadingErrorView.hidden = true

    _swipeFromTopRecognizer = UIScreenEdgePanGestureRecognizer(target: self, action: Selector("handleSwipeFromTop:"))
    _swipeFromTopRecognizer!.edges = UIRectEdge.Top
    _swipeFromTopRecognizer!.delegate = self
    self.view.addGestureRecognizer(_swipeFromTopRecognizer!)

    _progressView.hidden = true

    var urlAsString = "\(webpageURL!)"
    loadURL(urlAsString)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

// UI Control Functions

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

@IBAction func closeReadingView(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

func closeButtonEnabled(bool:Bool) {
    _closeButton.enabled = bool
}

func userContentController(userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage) {
    if(message.name == "callbackHandler") {
        println("JavaScript is sending a message \(message.body)")
    }
}


// WebView Functions

func webView(webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
    _loadingErrorView.hidden = true
    _isWebViewLoading = true
    _progressView.hidden = false
    _progressView.progress = 0
    _progressTimer = NSTimer.scheduledTimerWithTimeInterval(0.01667, target: self, selector: "progressTimerCallback", userInfo: nil, repeats: true)
    _loadingTimer = NSTimer.scheduledTimerWithTimeInterval(30, target: self, selector: "loadingTimeoutCallback", userInfo: nil, repeats: false)
}

func loadingTimeoutCallback() {
    _webView?.stopLoading()
    handleWebViewError()
}

func webView(webView: WKWebView, didCommitNavigation navigation: WKNavigation!) {
    _isCurrentPageLoaded = true
    _loadingTimer!.invalidate()
    _isWebViewLoading = false

    if self._webView!.URL == webpageURL! {
        handleWebViewError()
        println(webpageURL!)
        println(self._webView!.URL!)
    } else {
        println("Page was loaded successfully")
        println(webpageURL!)
        println(self._webView!.URL!)
    }
}

func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
    _isCurrentPageLoaded = true
    _loadingTimer!.invalidate()
    _isWebViewLoading = false
}

func webView(webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: NSError) {
    if let newFrameLoading = _isMainFrameNavigationAction {
        } else {
        handleWebViewError()
    }
}

func webView(webView: WKWebView, didFailNavigation navigation: WKNavigation!, withError error: NSError) {
    if let newFrameLoading = _isMainFrameNavigationAction {
        } else {
        handleWebViewError()
    }
}

func webView(webView: WKWebView, decidePolicyForNavigationAction navigationAction: WKNavigationAction, decisionHandler: (WKNavigationActionPolicy) -> Void) {
    if (navigationAction.targetFrame == nil && navigationAction.navigationType == .LinkActivated) {
        _webView!.loadRequest(navigationAction.request)
    }
    _isMainFrameNavigationAction = navigationAction.targetFrame?.mainFrame
    decisionHandler(.Allow)
}

func handleWebViewError() {
    _loadingTimer!.invalidate()
    _isCurrentPageLoaded = false
    _isWebViewLoading = false
    displayLoadingErrorMessage()
}

func progressTimerCallback() {
    if (!_isWebViewLoading) {
        if (_progressView.progress >= 1) {
            _progressView.hidden = true
            _progressTimer?.invalidate()
        } else {
            _progressView.progress += 0.2
        }
    } else {
        _progressView.progress += 0.003
        if (_progressView.progress >= 0.95) {
            _progressView.progress = 0.95
        }
    }
}

func loadURL(urlString: String) {
    let addrStr = httpifyString(urlString)
    let readingAddr = addrStr.stringByAddingPercentEncodingForFormUrlencoded()!
    let addr = NSURL(string: "http://mobilizer.instapaper.com/m?u=\(readingAddr)")
    if let webAddr = addr {
        let req = NSURLRequest(URL: webAddr)
        _webView!.loadRequest(req)
    } else {
        displayLoadingErrorMessage()
    }

}

func httpifyString(str: String) -> String {
    let lcStr:String = (str as NSString).lowercaseString
    if (count(lcStr) >= 7) {
        if (lcStr.rangeOfString("http://") != nil) {
            return str
        } else if (lcStr.rangeOfString("https://") != nil) {
            return str
        }
    }
    return "http://"+str
}


func displayLoadingErrorMessage() {
    _loadingErrorView.hidden = false
}

func handleGoBackPan(sender: UIScreenEdgePanGestureRecognizer) {
    if (sender.state == .Ended) {
            _webView!.goBack()
    }
}

func handleGoForwardPan(sender: AnyObject) {
    if (sender.state == .Ended) {
            _webView!.goForward()
    }
}

func handleSwipeFromTop(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
    coordinator.animateAlongsideTransition({ context in
        self._webView!.frame = CGRectMake(0, 0, size.width, size.height)
    }, completion: nil)
}

}

And here are some screenshots to demonstrate the issue: This is the view after it finished loading, working correctly:

This is the view after rotating the device to landscape:

And this is the scroll location after rotation:

Using self.view = _webView makes the view resize correctly, but ignores all the views on the Storyboard (since the View's contents are being rewritten).

How can I fix this issue (without rewriting self.view)?

Answer 1

I managed to solve the problem by using this line of code:

self._webView!.autoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight

:)

Answer 2

I'm posting an answer for Objective-C, just in case if someone comes here looking for it

[self.webView setAutoresizingMask:UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth];

Answer 3

In fact, as WKWebView can only be added programmatically, it happens to have the autoresizing mask to constraints flag enabled by default (when adding components and constraints inside Interface Builder, it's usually disabled for you). I think the correct solution would be:

webView?.translatesAutoresizingMaskIntoConstraints = false

after adding the constraints/anchors.

Answer 4

swift 3 version:

webView?.autoresizingMask = [.flexibleWidth, .flexibleHeight]