Disable magnification gesture in WKWebView - ios

Question

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.

Answer 1

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
}
}

Answer 2

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
}
}

Answer 3

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.

Answer 4

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)
}
}

Answer 5

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
}
}

Answer 6

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
}
}

Answer 7

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
}
}

Answer 8

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>

Answer 9

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)
}

Answer 10

Swift 2.0
extension WKWebView {
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
return nil
}
}

Answer 11

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

Answer 12

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;
}
}

Answer 13

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

Answer 14

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())
}

Answer 15

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)

Answer 16

We need to change the delegate call with following signatures in XCode 8:
override func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return nil
}

Answer 17

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;
}
}
}

Answer 18

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")
}

Answer 19

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;
}

Answer 20

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)

Answer 21

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.