:Use HTTPDNS for WKWebView on iOS

1. Introduction

In Use HTTPDNS in native scenarios on iOS, you learned how to use HTTPDNS in native iOS scenarios for anti-hijacking, precise scheduling, and instant DNS resolution.

WKWebView, the modern WebKit-based web view that replaced UIWebView, is another iOS scenario that frequently involves network requests. Integrating HTTPDNS with WKWebView improves network security and performance.

2. Current technology

Technical solutions for integrating HTTPDNS with WKWebView have evolved alongside iOS:

• Before iOS 17.0: Apple provided no official hook interfaces for WKWebView DNS resolution or custom network requests, requiring complex solutions based on private API hooking.

• iOS 17.0 and later: Apple introduced the ProxyConfiguration API, which provides official proxy configuration for WKWebView. This API reliably intercepts all network requests, enabling seamless HTTPDNS integration.

According to Apple (as of June 4, 2025), iOS 17 and later runs on over 85% of iPhones. HTTPDNS brings anti-hijacking, precise scheduling, and instant resolution to WKWebView. This solution covers most users, and users on older versions gain the capability automatically upon upgrade.

3. Recommended solution: Local proxy-based solution for iOS 17+

source 'https://github.com/aliyun/aliyun-specs.git'

target 'yourAppTarget' do
    use_framework!
    
    pod 'AlicloudHTTPDNS', 'x.x.x'
    pod 'EMASLocalProxy', 'x.x.x'
end

#import <EMASLocalProxy/EMASLocalProxy.h>
#import <AlicloudHttpDNS/AlicloudHttpDNS.h>

// Create a WKWebViewConfiguration
WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];

// Configure the DNS resolver
[EMASLocalHttpProxy setDNSResolverBlock:^NSArray<NSString *> *(NSString *hostname) {
    // Get the HTTPDNS service instance
    HttpDnsService *httpdns = [HttpDnsService sharedInstance];
    HttpdnsResult *result = [httpdns resolveHostSyncNonBlocking:hostname byIpType:HttpdnsQueryIPTypeBoth];

    if (result && (result.hasIpv4Address || result.hasIpv6Address)) {
        NSMutableArray<NSString *> *allIPs = [NSMutableArray array];
        if (result.hasIpv4Address) {
            [allIPs addObjectsFromArray:result.ips];
        }
        if (result.hasIpv6Address) {
            [allIPs addObjectsFromArray:result.ipv6s];
        }
        NSLog(@"HTTPDNS resolution successful. Domain name: %@, IP: %@", hostname, allIPs);
        return allIPs;
    }

    NSLog(@"HTTPDNS resolution failed. Domain name: %@", hostname);
    return nil;
}];

// Set the log level
[EMASLocalHttpProxy setLogLevel:EMASLocalHttpProxyLogLevelDebug];

// Configure the WebView proxy
BOOL proxyConfigured = [EMASLocalHttpProxy installIntoWebViewConfiguration:config];
if (proxyConfigured) {
    NSLog(@"WebView proxy configuration successful.");
} else {
    NSLog(@"WebView proxy configuration failed. Using system network.");
}

WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds configuration:config];

4. Global NSURLProtocol interception solution

This was the earliest feasible option for integrating HTTPDNS with iOS WebView. It has a very high barrier to entry and is not very effective. It persisted because iOS offered no alternatives in its early years. The approach uses NSURLProtocol to intercept network requests from NSURLConnection/NSURLSession, including WKWebView requests, and applies HTTPDNS resolution. The steps are as follows:

1. Register a custom NSURLProtocol to intercept WKWebView network requests. The custom protocol takes over data sending, receiving, and redirection, then feeds results back to the original request.

   [NSURLProtocol registerClass:[HttpDnsNSURLProtocolImpl class]];

2. Overview of the custom NSURLProtocol processing flow:

   • In canInitWithRequest, filter the requests that require HTTPDNS domain name resolution.

   • After the request is intercepted, perform HTTPDNS domain name resolution.

   • After resolution is complete, replace the URL.host field and the HTTP Header Host field, similar to a normal request. Then, take over the data sending, receiving, redirection, and other processing for this request.

   • Use the NSURLProtocol interface to feed the request processing results back to the original WebView request.

3. The custom NSURLProtocol implementation is available in HttpDnsNSURLProtocolImpl.m in the demo project.

5. Solution summary and comparison

This topic covers two solutions for integrating HTTPDNS with WKWebView on iOS: the local proxy solution (iOS 17+) and global NSURLProtocol interception.

The following table compares the two solutions:

For stability, low maintenance, and future-proofing, we strongly recommend the local proxy solution (iOS 17+).

With iOS 17+ adoption exceeding 85%, this solution serves most users at minimal cost. It prevents domain hijacking and improves network performance with long-term official API support. Devices on earlier iOS versions fall back to default system networking and gain HTTPDNS benefits automatically upon upgrade.

The NSURLProtocol solution carries inherent complexity and uncertainty. Use it only with specific requirements, deep technical expertise, and thorough testing.