WKWebView displays content wrong after orientation change - ios

I am fairly new to iOS development and I'm using a WKWebView to display a page that plays a video using the Vimeo Player. When the app starts up, it shows the view correctly, no matter what orientation it is currently in. However, once I change the orientation the view will either look zoomed in or has whitespace below the video.
The annoying thing about this is that it's not consistent. Sometimes the view displays correctly, sometimes it doesn't. If I try to zoom the view in or out or try to scroll when using the app it usually corrects itself, but even that does not seem to be 100% reliable.
Some screenshots (tested on iPad 2):
Landscape orientation (correct):
Portrait orientation (correct):
Landscape orientation (incorrect):
Portrait orientation (incorrect):
And the code used to produce this result:
import Foundation
import UIKit
import WebKit
class VideoViewController : UIViewController, WKScriptMessageHandler {
#IBOutlet var containerView : UIView! = nil
var webView: WKWebView?
override func loadView() {
super.loadView()
self.webView = WKWebView()
let contentController = WKUserContentController();
let scaleToFit = WKUserScript(source: "var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width, initial-scale=1.0'); document.getElementsByTagName('head')[0].appendChild(meta);", injectionTime: WKUserScriptInjectionTime.AtDocumentStart, forMainFrameOnly: true)
contentController.addUserScript(scaleToFit)
contentController.addScriptMessageHandler(self, name: "callbackHandler")
self.view = webView!
}
override func viewDidLoad() {
super.viewDidLoad()
refreshUI()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func refreshUI() {
let url = NSURL(string: "https://photofactsacademy.nl/api/vp.asp?id=152839850")
let requestObj = NSURLRequest(URL: url!)
webView!.loadRequest(requestObj)
}
func userContentController(userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage) {
if(message.name == "callbackHandler") {
print("JavaScript is sending a message \(message.body)")
}
}
}
I looked through SO for WKWebView and orientation change and didn't find anything that helped me.
Your help is appreciated.

Can you try this
wkWebView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

I was able to solve this problem by injecting a javascript reload call like this:
Swift:
func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
coordinator.animateAlongsideTransition(nil, completion: {
//Reset Frame of Webview
webView.evaluateJavaScript("location.reload();", completionHandler: nil)
}
Objective C:
-(void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator {
//Reset Frame of Webview
[_webView evaluateJavaScript:#"location.reload();" completionHandler:^(id _Nullable obj, NSError * _Nullable error) {
NSLog(#"error:%#", error);
}];
}

You don't need to reload the entire web page. You just need to reload its input views. Make sure you have set constraints to web view properly and then add below code while changing orientation.
// Reload inputs so that webview can adjust its content according to orientation
[self.webView reloadInputViews];

After few hours of struggling, this is what worked for me:
<header><meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no, shrink-to-fit=no'></header><body style='margin: 0px; padding: 0px; width:100%; height:100%;'>...
Set width and height of both body and your video element to 100% and disable user scaling through header tag.

Related

How to make transparent background WKWebView in Swift

I want a transparent web page in swift, so I have tried the below code according to this answer. Still, I am not getting a transparent web page. nothing changes in webview colour.. may I know why??
where am I going wrong? please help me in below code.
Total code:
import UIKit
import WebKit
class WebviewViewController: UIViewController {
#IBOutlet weak var testWebView: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
guard let url = URL(string: "https://developer.apple.com/swift/") else { return }
let request = URLRequest(url: url)
testWebView.load(request)
// Do any additional setup after loading the view.
self.testWebView = WKWebView()
self.testWebView!.isOpaque = false
self.testWebView!.backgroundColor = UIColor.clear
self.testWebView!.scrollView.backgroundColor = UIColor.clear
}
}
Please help me with the code.
the code to make transparent background is as follow what you already added.
self.testWebView!.backgroundColor = UIColor.clear
now question is you added right code already then why you are not getting reliable output ..?
Also , if you try
self.testWebView!.alpha with any value, it will affect all of WebPages as WkWebView is a single view and changing it's alpha will also affect the components within...
it happened because the page you load in WebViewController has some HTML and CSS code, you make your WebViewController transparent but because of that HTML &CSS you can't see it's transparency as each webpage has it's own background color settings (which is merely impossible to change for each webpage)
I hope you will understand and it will help you ...:)
as I see, you use storyboard (#IBOutlet) and you can use Storyboard for setting your WKWebView:
And about code. This is enough for the result. You shouldn't set again self.testWebView = WKWebView(), because you use storyboard and you can set isOpaque with storyboard. As result:
class ViewController: UIViewController, WKNavigationDelegate {
#IBOutlet var webView: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
webView.navigationDelegate = self
let url = URL(string: "https://developer.apple.com/swift/")!
webView.load(URLRequest(url: url))
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
let js = "(function() { document.body.style.background='transparent'; })();"
webView.evaluateJavaScript(js) { (_, error) in
print(error)
}
}
}
and evaluateJavaScript helped to add transparency for background:

How to vertically center the text in WKWebView?

I am using WKWebView in my iOS (swift) app and i am using loadHTMLString(string, baseURL: ). Now the problem is that I want the HTML to be vertically centered in the frame. The text is variable in length. How can I do that?
This is the screenshot of the HTML from Xcode:
This is image of the output. The top HTML is on the upper side, I want it to be centrally aligned in its view (the view is 300 points from the top):
Try using this HTML with inline CSS, you can replace the stuff in between the divs that you want centered:
<div style="display:flex;align-items:center;height:100%;justify-content:center;">
<p>You content here</p>
</div>
This code works for me using Swift 3.0 on an iPhone 6 simulator
import UIKit
import WebKit
class ViewController: UIViewController {
var webView:WKWebView?
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool) {
webView = WKWebView(frame: self.view.frame)
self.view.addSubview(webView!);
addHTML()
}
func addHTML() {
let html = "<html><body><div style='height:100%;background-color:black;display:flex;align-items:center;justify-content:center;'><p style='color:white;font-size:100px;'>Asleepace</p></div></body></html>";
webView!.loadHTMLString(html, baseURL: nil)
}
}
Example Output

WKWebView, scrolling the web page to top

I tried this, which should work but doesn't:
webView.scrollView.setContentOffset(CGPoint(x: 0, y: 0), animated: false)
I am working on a browser and have a couple of webViews in kept in stack. Some sites work as expected, start at the top, some do not.
Starts at top: http://leagueoflegends.com/
This one starts a little down, have to manually scroll up: http://euw.leagueoflegends.com/
Extra note, this problem never happens to the first webView. Even if I load the 2nd link and show it as first webView, it doesn't scroll to the middle.
I had a very similar problem when rotating my WKWebView.
After rotation to landscape the view is automatically scrolled to the middle.
I use following workaround to scroll to the top of the page again after rotation:
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
coordinator.animate(alongsideTransition: nil, completion: { (context) in
self.webKitView.evaluateJavaScript("window.scrollTo(0,0)", completionHandler: nil)
})
}
In your case it should work to call this directly after you load your URL.
webKitView.evaluateJavaScript("window.scrollTo(0,0)", completionHandler: nil)
Or if your problem occurs when navigating within the WKWebView, you could use a WKNavigationDelegate (I have not tested this) :
override func viewDidLoad() {
super.viewDidLoad()
// load content of webKitView here and set as view or add as subview
webKitView.navigationDelegate = self
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
webKitView.evaluateJavaScript("window.scrollTo(0,0)", completionHandler: nil)
}
Our app uses multiple WKWebView instances and we have also experienced this problem of some pages randomly scrolling to some location down the page.
We were able to work around the problem by having the next webView which will be loading the next page attached to the window hierarchy before loading the URL.
WKWebView* nextWebView = [WKWebView new];
[[[UIApplication sharedApplication] keyWindow] addSubview:webView.view];
[[[UIApplication sharedApplication] keyWindow] sendSubviewToBack:webView.view];
Then when you load your URL:
[nextWebView.view removeFromSuperview];
[controller.view addSubview: nextWebView.view];
I encountered this too. Finally, I fixed this way:
if #available(iOS 11, *) {
webView.scrollView.contentInsetAdjustmentBehavior = .never
}
If you have this issue on iOS 11, try this.
Before iOS 11.0, UIWebView was avilable with delegates to indicate that loading of webView is finished and we can do any operation after loading has been finished.
Now we have WKWebView which doesn't provide any delegate method to notify once your webView has finished loading. Due to this if we do following piece of code then it will not work:
let myURL = URL(string: "https://www.google.com")
let myRequest = URLRequest(url: myURL!)
webView.load(myRequest)
webView.scrollView.setContentOffset(CGPoint(x: 0, y: 0), animated: false)
In this case, webView.load() is a asynchronous function which gets called and code moves further without waiting for its completion. Due to this your call for setContentOffset work but after that when webView finish loading it reset the ContentOffset to default, which is actually (0,0) but I am not sure why your WebView doesn't load from top. But doing code in following manner will may help you:
Extend to WKNavigationDelegate and implement didFinish navigation method in your ViewController and call setContentOffset in that method.
class ViewController: UIViewController, WKNavigationDelegate {
override func viewDidLoad() {
let myURL = URL(string: "https://www.google.com")
let myRequest = URLRequest(url: myURL!)
webView.load(myRequest)
webView.navigationDelegate = self
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
webView.scrollView.setContentOffset(CGPoint(x: 0, y: 0), animated: false)
}
}
I would try to use javascript doc for scrolling to top:
NSString *script = #"window.scrollTo(0, 0)";
// UIWebView
// [webView stringByEvaluatingJavaScriptFromString:script];
// WKWebView
[webView evaluateJavaScript:script completionHandler:NULL];
Swift 4
This function is part of the WKWebView's UIScrollView and scrolls to a given rectangle.
scrollRectToVisible(_ rect: CGRect, animated: Bool)
A code example would look like:
let rect: CGRect = CGRect(x: 0, y: 0, width: 1, height: 1)
webView.scrollView.scrollRectToVisible(rect, animated: true)
This seems to happen if the WKWebView is not fully initialized or sized when asked to display a web page.
In my case, I created the web view during loadView in a UIViewController. If I then requested to navigate to a web page during viewDidLoad, the web view appeared scrolled partway down the page. I was able to fix the problem by moving the html request into viewWillAppear: (which is later in the view controller lifecycle).

UIWebView - white background before loading content

I have a question. I have a menu, when I click on it, it will load content remotely from URL via UIWebView.
When I try on simulator, before loading the content, there's a white background and then loads my HTML Page (which has dark background)
Demo:
You can see that white flash, when I click on "KALENDER"
How can I fix this issue?
My UIWebView looks like this:
let myWebView:UIWebView = UIWebView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height))
myWebView.loadRequest(NSURLRequest(URL: NSURL(string: "http://website.com/test.html")!))
self.view.addSubview(myWebView)
Thank you!
So, what I did, is, added:
myWebView.opaque = false
myWebView.backgroundColor = UIColor.clearColor()
and at controller, I unchecked this from "View"
You cannot set background color to your webView.
You should try following steps:
1. write following in your viewDidLoad - Setting delegate and hiding webView.
webView.delegate = self
webView.hidden = YES
2. Write delegate - shouldStartLoadWithRequest - hiding webView when loading starts.
func webView(webView: UIWebView!, shouldStartLoadWithRequest request: NSURLRequest!, navigationType: UIWebViewNavigationType) -> Bool {
webView.hidden = YES
return true;
}
3. Write delegate - webViewDidFinishLoad - Show webView when loading Ends.
func webViewDidFinishLoad(webView: UIWebView!) {
webView.hidden = NO
print("Webview did finish load")
}
Hope this will help you....
You could load your own html document, which uses the color you need.
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
let htmlString = "<html><body bgcolor=\"#ABCDEF\"></body></html>"
webView.loadHTMLString(htmlString, baseURL: nil)
}

Disable magnification gesture in WKWebView

I'm looking for a way to disable the "pinch to zoom" magnification gesture on the iOS implementation of WKWebView. There is a magnification BOOL property available for OS X but it doesn't seem to be available on iOS.
WKWebView.h
#if !TARGET_OS_IPHONE
/* #abstract A Boolean value indicating whether magnify gestures will
change the web view's magnification.
#discussion It is possible to set the magnification property even if
allowsMagnification is set to NO.
The default value is NO.
*/
#property (nonatomic) BOOL allowsMagnification;
I've, also, tried look at the WKWebView's gesture recognizers but that seems to be turning up an empty array. I'm assuming the actual recognizers are bured deeper in the component's structure (fairly complex, by the looks of it) and would rather not go digging for them if at all possible.
I know of possible hacks that could potentially disable the gesture from firing (selectively passing gestures to the WebView, add child view to capture pinch gesture, etc) but I've always found those introduce lag into the event and want to keep the implementation as clean/hack free as possible.
You can prevent your users from zooming by setting the delegate of your WKWebKit's UIScrollView and implementing viewForZooming(in:) as in the following:
class MyClass {
let webView = WKWebView()
init() {
super.init()
webView.scrollView.delegate = self
}
deinit() {
// Without this, it'll crash when your MyClass instance is deinit'd
webView.scrollView.delegate = nil
}
}
extension MyClass: UIScrollViewDelegate {
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return nil
}
}
I have tried setting minimumZoomScale and maximumZoomScale properties of UIScrollView to 1 or isMultipleTouchEnabled property of UIView to false or returning nil from invoking viewForZooming(in:) of UIScrollViewDelegate but none worked. In my case, after several trial and error, the following works in my case [Tested on iOS 10.3]:
class MyViewController: UIViewController {
var webView: WKWebView?
override viewDidLoad() {
super.viewDidLoad()
//...
self.webView.scrollView.delegate = self
//...
}
}
extension MyViewController: UIScrollViewDelegate {
func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?) {
scrollView.pinchGestureRecognizer?.isEnabled = false
}
}
The below answer no longer works in iOS 10 beta.
To improve accessibility on websites in Safari, users can now
pinch-to-zoom even when a website sets user-scalable=no in the
viewport.
WKWebView seems to respect the viewport meta tag the same way Mobile Safari does (as to be expected). So, I found injecting that tag into the DOM through javascript after a page load does the trick. I would be weary of this solution unless you know exactly what HTML is being loaded into the webview, otherwise I suspect it would have unintended consequences. In my case, I'm loading HTML strings, so I can just add it to the HTML I ship with the app.
To do it generically for any webpage:
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation {
NSString *javascript = #"var meta = document.createElement('meta');meta.setAttribute('name', 'viewport');meta.setAttribute('content', 'width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no');document.getElementsByTagName('head')[0].appendChild(meta);";
[webView evaluateJavaScript:javascript completionHandler:nil];
}
It might be wise to take a look at what kind of navigation has just been completed, since only a new page will need this javascript executed.
Complete working code to disable zooming in WkWebView in Swift.
import UIKit
import WebKit
class ViewController: UIViewController, WKUIDelegate {
var webView : WKWebView!
override func loadView() {
let webConfiguration = WKWebViewConfiguration()
webView = WKWebView(frame: .zero, configuration:webConfiguration)
webView.uiDelegate = self
let source: String = "var meta = document.createElement('meta');" +
"meta.name = 'viewport';" +
"meta.content = 'width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no';" +
"var head = document.getElementsByTagName('head')[0];" + "head.appendChild(meta);";
let script: WKUserScript = WKUserScript(source: source, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
webView.configuration.userContentController.addUserScript(script)
view = webView
}
override func viewDidLoad() {
super.viewDidLoad()
let myUrl = URL(string: "https://www.google.com")
let myRequest = URLRequest(url: myUrl!)
webView.load(myRequest)
}
}
The native solutions were not working for me, and injecting JS is not ideal. I noticed that when a zoom occurs and my delegate is called, the pinchGestureRecognizer is enabled even though I disabled it when initializing the webview. To fix this, I set it to disabled whenever a zoom starts:
extension ViewController: UIScrollViewDelegate {
// disable zooming in webview
func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?) {
scrollView.pinchGestureRecognizer?.isEnabled = false
}
}
Full Swift 3 / iOS 10 version of Landschaft's answer:
import UIKit
import WebKit
class MyViewController: UIViewController, UIScrollViewDelegate {
var webView = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(webView)
webView.scrollView.delegate = self
}
// Disable zooming in webView
func viewForZooming(in: UIScrollView) -> UIView? {
return nil
}
}
You can use UIScrollViewDelegate for this. First assign delegate to your webview in viewDidLoad() or any other suitable method as:
class LoginViewController: UIViewController, WKUIDelegate, UIScrollViewDelegate {
override func viewDidLoad() {
webView.scrollView.delegate = self
}
//Add this delegate method in your view controller
func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?) {
scrollView.pinchGestureRecognizer?.isEnabled = false
}
}
In case you display a local html you could just modify this html and put this meta tag to your html:
<head>
<meta content='width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0' name='viewport' />
</head>
A simple way to prevent zooming
override func viewDidLoad() {
super.viewDidLoad()
webView.scrollView.delegate = self
}
func scrollViewDidZoom(_ scrollView: UIScrollView) {
scrollView.setZoomScale(1.0, animated: false)
}
Swift 2.0
extension WKWebView {
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
return nil
}
}
If it's not important for you to handle links inside html (say you want to display text only) the simplest would be to turn off user interaction
webView.userInteractionEnabled = false
this is how I disabled zoom for Swift3 view controller for one-webview-only app
import UIKit
import WebKit
class ViewController: UIViewController, WKNavigationDelegate, UIScrollViewDelegate {
#IBOutlet var webView: WKWebView!
override func loadView() {
webView = WKWebView()
webView.navigationDelegate = self
view = webView
}
override func viewDidLoad() {
super.viewDidLoad()
webView.scrollView.delegate = self
}
func viewForZooming(in: UIScrollView) -> UIView? {
return nil;
}
}
I don't have enough reputation to add comments to answers, but I wanted to mention that Kevin's solution (meta viewport) no longer works in iOS 10 beta. Landschaft's solution is working for me, though!
Since the JS solution uses W3C standards, it should always be supported.
Ah, Kevin, I wish that were how these things worked.
More here: https://stackoverflow.com/a/37859168/1389714
Disable double tap to zoom gesture by require failure of gesture recognizer. It will prevent the browser to take action when user double tap.
import UIKit
class DisableDoubleTapRecognizer : UITapGestureRecognizer, UIGestureRecognizerDelegate{
override init(target: Any?, action: Selector?) {
super.init(target: target, action: action)
}
init() {
super.init(target:nil, action: nil)
self.numberOfTapsRequired = 2;
self.delegate = self;
}
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true;
}
}
//in your view controller
override func viewDidLoad() {
super.viewDidLoad()
webView.addGestureRecognizer(DisableDoubleTapRecognizer())
}
Here's a slightly modified version of Gulshan Kumar's answer that worked for me in iOS 12.1.2, and it also prevents zooming due to double-taps and rotation. In my example, I just inject the script directly into the web view. I adjusted the scale to 60%, and there's no need to use concatenation in building up the source string.
let source = "var meta = document.createElement('meta'); meta.name = 'viewport'; meta.content = 'width=device-width, initial-scale=0.6, maximum-scale=0.6, user-scalable=no'; var head = document.getElementsByTagName('head')[0]; head.appendChild(meta);"
let script = WKUserScript(source: source, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
webView.configuration.userContentController.addUserScript(script)
We need to change the delegate call with following signatures in XCode 8:
override func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return nil
}
The application I work on needed the view to be zoomed by Javascript. The accepted answer blocked zooming by JavaScript from inside the page too.
I only needed to disable pinch gesture by the user of the appliction. The only solution I've found is to disable the gesture of the web view after the page has loaded:
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
/* disable pinch gesture recognizer to allow zooming the web view by code but prevent zooming it by the user */
for (UIGestureRecognizer *gr in self.webView.scrollView.gestureRecognizers) {
if ([gr isKindOfClass:[UIPinchGestureRecognizer class]]) {
gr.enabled = NO;
}
}
}
If it is better to disbaled the Pinch zoom when the webpage finish loading, and it can also specify which particular URL is going to be disbaled
public func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
if let url = webView.url, url.absoluteString == "***" {
webView.scrollView.pinchGestureRecognizer?.isEnabled = false
}
print("finish")
}
For obj-c., add UIScrollViewDelegate protocol.
/* somewhere else, for example in viewDidLoad() */
_wkWeb.scrollView.delegate = self;
..
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view {
scrollView.pinchGestureRecognizer.enabled = NO;
}
This worked for me. https://gist.github.com/paulofierro/5b642dcde5ee9e86a130
let source: String = "var meta = document.createElement('meta');" +
"meta.name = 'viewport';" +
"meta.content = 'width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no';" +
"var head = document.getElementsByTagName('head')[0];" + "head.appendChild(meta);";
let script: WKUserScript = WKUserScript(source: source, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
let userContentController: WKUserContentController = WKUserContentController()
let conf = WKWebViewConfiguration()
conf.userContentController = userContentController
userContentController.addUserScript(script)
let webView = WKWebView(frame: CGRect.zero, configuration: conf)
If the webview is user for read-only purposes, i.e, just for displaying the web content use
webView.isUserInteractionEnabled = false
By this the zoom gesture won't work on it.

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