WKWebView loads HTML content too slowly in iOS 9 using swift

Question

I have been trying to integrate the WKWebView as a subview of another webview in a UIViewController. I've been able to load the content and communicate properly with the swift and JavaScript. However, the loading time of the HTML content without any data manipulation takes close to 2 seconds.

I have also tested loading the WKWebView with just an empty body of HTML without any scripts loading. This still takes 600 milliseconds to load.

The time taken difference between viewDidLoad and the webView (webView: WKWebView, didFinishNavigation navigation: WKNavigation!)** Is 600 ms, if even the HTML contains an empty body.

viewDidLoad function of the ViewController

override func viewDidLoad() {
    NSLog("started - %@.%@", String(self.dynamicType), __FUNCTION__)
    super.viewDidLoad()
    
    let wkConfiguration: WKWebViewConfiguration = WKWebViewConfiguration()
    let userController: WKUserContentController = WKUserContentController()
    wkConfiguration.userContentController = userController
    wkConfiguration.processPool = VCWKWebView.wkProcess
    self.wkWebView = VCWKWebView(frame: self.webView.bounds,configuration: wkConfiguration)
    if let wkWebView = self.wkWebView {
        self.webView.addSubview(wkWebView)
        wkWebView.translatesAutoresizingMaskIntoConstraints = false
        let height = NSLayoutConstraint(item: wkWebView, attribute: .Height, relatedBy: .Equal, toItem: self.webView, attribute: .Height, multiplier: 1, constant: 0)
        let width = NSLayoutConstraint(item: wkWebView, attribute: .Width, relatedBy: .Equal, toItem: self.webView, attribute: .Width, multiplier: 1, constant: 0)
        webView.addConstraints([height, width])
        //wkWebView.delegate = self
        wkWebView.navigationDelegate = self
        wkWebView.loadContent()
    }
    
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
    
    NSLog("ended - %@.%@", String(self.dynamicType), __FUNCTION__)
}

VCWKWebView class:

class VCWKWebView: WKWebView  {
    
    static let wkProcess: WKProcessPool = WKProcessPool()
    
    private static let _url: NSURL = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("index", ofType: "html",inDirectory:"www")!)

    private static let _accessUrl: NSURL = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("www", ofType: nil)!)

    
    func loadContent(){
        NSLog("started - %@.%@", String(self.dynamicType), __FUNCTION__)
        if #available(iOS 9.0, *) {
            self.loadFileURL(VCWKWebView._url, allowingReadAccessToURL: VCWKWebView._accessUrl)
        } else {
            // Fallback on earlier versions
        }
        NSLog("ended - %@.%@", String(self.dynamicType), __FUNCTION__)
    }
    
    override init(frame: CGRect, configuration: WKWebViewConfiguration) {
        super.init(frame:frame, configuration:configuration)
    }
    
    convenience init(frame: CGRect){
        let wkConfiguration: WKWebViewConfiguration = WKWebViewConfiguration()
        self.init(frame:frame,configuration:wkConfiguration)
    }
    
    deinit{
        print("deinit of VCWKWebView is called")
    }
}

I'm having a similar problem replacing UIWebView with WKWebView for some javascript intensive web pages. WKWebView is much slower which seems contrary to all the advice about them. Anyone got any ideas? — Son of a Beach, Mar 09 '17 at 01:08
What about stating the webview once, and reuse it across your application? You could have it ready beforehand. — chq, Mar 26 '23 at 04:10
@chq how does one create a webview in one place, and then use it elsewhere? — MMazzon, Apr 01 '23 at 11:50

score 0 · Answer 1 · answered Jun 21 '23 at 06:38

0

I think there are two ways.

#1. Optimize your HTML, CSS, and JavaScript code.

#2. You need to implement WKWebView delegate functions. And you need to show the Webview content after loaded the webview content.

answered Jun 21 '23 at 06:38

Venus

453
2
9

score 0 · Answer 2 · answered Aug 28 '23 at 06:11

This usually happens because of CSS used in rendering web page. It is default behavior when loading page locally. We can also consider that in first load, UIWebview doesn't have cache to this and create cache for that page.

Please share your html part as well so I could check

WKWebView loads HTML content too slowly in iOS 9 using swift

2 Answers2