如何在iOS Swift中设置延迟？

Question

func create()
        {
            self.Instance!.viewController!.loadCategory(category: 0)

            /*
            repeat
            {
                print("Loading category section!")
            }
            while (self.Instance!.viewController!.isLoading!)
            */
        }

The above code shows that I can have a delay set until isLoading is false; however, it never becomes false because it locks the thread.

How can I have this in the background?

Thanks

LoadCategory is using wkwebview to load a website's category page and sets isLoading to true when loading the content of the webpage and sets it to false when it is all done loading

 func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!)
    {
        print("Finished navigating to url \(String(describing: webView.url))")

        self.isLoading = false
    }

This is my function which sets it to self.isLoading to false after finished loading content.

Answer 1

Grand Central Dispath

In Swift you can execute a closure after a given delay using Grand Central Dispatch

Here's the code

DispatchQueue.main.asyncAfter(deadline: .now() + 2) { 
    print("This will be executed 2 seconds in the future")
} 

Don't forget to import Foundation

Answer 2

A WKWebView can have a navigation delegate ( WKNavigationDelegate ). That delegate can implement a method called webView:didFinishNavigation ( https://developer.apple.com/reference/webkit/wknavigationdelegate/1455629-webview ) which will tell you when the web view is finished loading content.

Based on your code, your viewController can probably be set up as the delegate for the web view and can perform whatever actions you would like after the content is loaded.