In this article, we will explore how to use the WKNavigationDelegate protocol in your iOS app to manage and respond to navigation changes in a WKWebView. This protocol allows you to handle various events during the loading of web content, such as page load progress, errors, and redirects.

What is WKNavigationDelegate?

WKNavigationDelegate is a protocol provided by Apple's WebKit framework. It defines a set of methods that you can implement to manage and respond to navigation actions in a WKWebView. By conforming to this protocol, you can control how your app interacts with web content and handle events like page load starts, finishes, and failures.

Setting Up WKWebView and WKNavigationDelegate

First, let's create a simple iOS app with a WKWebView and set up the WKNavigationDelegate.

Step 1: Create a New iOS Project

1. Open Xcode and create a new Single View App project.
2. Name your project and choose Swift as the language.
3. Save your project.

Step 2: Add WKWebView to Your View

1. Open Main.storyboard.
2. Drag a WKWebView from the Object Library to your view controller.
3. Set constraints to position the WKWebView as needed.

Step 3: Set Up the ViewController

1. Open ViewController.swift.
2. Import the WebKit framework.

import UIKit
import WebKit

3. Create an outlet for the WKWebView.

class ViewController: UIViewController {
    @IBOutlet weak var webView: WKWebView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Set the navigation delegate
        webView.navigationDelegate = self

        // Load a URL
        if let url = URL(string: "https://www.apple.com") {
            let request = URLRequest(url: url)
            webView.load(request)
        }
    }
}

4. Conform to the WKNavigationDelegate protocol.

extension ViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        print("Started loading")
    }

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        print("Finished loading")
    }

    func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
        print("Failed to load with error: \(error.localizedDescription)")
    }
}

Handling Navigation Events

By implementing the WKNavigationDelegate methods, you can handle various navigation events:

• webView(_:didStartProvisionalNavigation:): Called when the web view starts loading content.
• webView(_:didFinish:): Called when the web view finishes loading content.
• webView(_:didFail:withError:): Called when the web view fails to load content.

You can also implement other methods to handle redirects, authentication challenges, and more.

Example: Handling Redirects

To handle redirects, you can implement the webView(_:decidePolicyFor:decisionHandler:) method.

extension ViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        if let url = navigationAction.request.url {
            print("Redirecting to: \(url.absoluteString)")
        }
        decisionHandler(.allow)
    }
}

Conclusion

By using WKNavigationDelegate, you can gain fine-grained control over the navigation behavior of WKWebView in your iOS app. This allows you to handle loading progress, errors, redirects, and more, providing a better user experience.