CODEWITHSUNDEEP
iosswift
Anish Kumar D
Anish Kumar D

Reputation: 3

Unable to update height constraint of WKWebView - Autolayout

I added UILabel and WKWebView in vertical UIStackview and the distribution is set to fillProportionally. I am trying to set the web view height based on the content height. For that, I set the initial web view height as 0. Once the html content is loaded, I am trying to update the height constraint of web view to the scroll height. But I am getting auto layout constraint conflict issues.

//Adding WKWebView in UIStackView

let headerString = "<header><meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no'></header>"
        let htmlString = headerString + correctAnswer
        questionWebView.loadHTMLString(htmlString, baseURL: nil)
        stackView.addArrangedSubview(questionWebView)
        questionWebView.translatesAutoresizingMaskIntoConstraints = false;
        questionWebView.trailingAnchor.constraint(equalTo: stackView.trailingAnchor).isActive = true
        questionWebView.leadingAnchor.constraint(equalTo: stackView.trailingAnchor).isActive = true
        questionWebVieHeightAnchor = questionWebView.heightAnchor.constraint(equalToConstant: 0.0)
        questionWebVieHeightAnchor.isActive = true

I tried to update height constraint dynamically in webView didFinish method. But I am getting layout conflict issue.

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        webView.evaluateJavaScript("document.readyState", completionHandler: { (complete, error) in
            if complete != nil {
                webView.evaluateJavaScript("document.body.scrollHeight", completionHandler: { (height, error) in
                    print("Height is \(height as! CGFloat)")
                    self.questionWebVieHeightAnchor.constant = height
                    self.questionWebView.layoutIfNeeded()
                })
            }
        })
    }

Issue:

   Unable to simultaneously satisfy constraints.
        Probably at least one of the constraints in the following list is one you don't want. 
        Try this: 
            (1) look at each constraint and try to figure out which you don't expect; 
            (2) find the code that added the unwanted constraint or constraints and fix it. 
    (
        "<NSLayoutConstraint:0x600000a194a0 WKWebView:0x7f9363b5fa00.height == 200>",
        "<NSLayoutConstraint:0x600000ad2b70 WKWebView:0x7f9363b5fa00.height == 0>"
    )

    Will attempt to recover by breaking constraint 
    <NSLayoutConstraint:0x600000a194a0 WKWebView:0x7f9363b5fa00.height == 200>

Upvotes: 0

Views: 952

Answers (1)

andromedainiative
andromedainiative

Reputation: 4992

This won't work great I'm afraid. This is because when you add views to a stack view, the stack view will try to sort the constraints on itself. Based on the intrinsic content size of the views you added. I would probably not use a stack view if you need to update the web view content size.

Upvotes: 1

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