ios为什么我不能钩住WKCustomProtocol方法

Question

WKCustomProtocol是WebKit source code的类形式，我已经调试了它。它存在

HDWebURLProtocol，WKCustomProtocol超类是NSURLProtocol。我钩上了自己的类“ HDWebURLProtocol”，该类已成功，但是WKCustomProtocol不成功；

我使用Xcode 10.1，iOS 12.1模拟器，调试运行WebKit code

这是我的代码：

+ (void)exchange {

    Class WKCustomProtocolClass = object_getClass(NSClassFromString(@"WKCustomProtocol")); // HDWebURLProtocol

    SEL canInitWithRequest = NSSelectorFromString(@"canInitWithRequest:");
    SEL af_canInitWithRequest = NSSelectorFromString(@"fix_canInitWithRequest:");

    BOOL add1 = class_addMethod(WKCustomProtocolClass,
                                canInitWithRequest,
                                class_getMethodImplementation(WKCustomProtocolClass, canInitWithRequest),
                                "B@:@");

    BOOL add2 = class_addMethod(WKCustomProtocolClass,
                                af_canInitWithRequest,
                                (IMP)af_canInitWithRequest2,
                                "B@:@");

    NSLog(@"%d,%d", add1, add2);

    Method orgi = class_getClassMethod(WKCustomProtocolClass, canInitWithRequest);
    Method after = class_getClassMethod(WKCustomProtocolClass, af_canInitWithRequest);

    method_exchangeImplementations(orgi, after);
}

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"

BOOL af_canInitWithRequest2(id sender, SEL cmd, NSURLRequest *req) {
    SEL canInitWithRequest = NSSelectorFromString(@"fix_canInitWithRequest:");
    return [sender performSelector:canInitWithRequest withObject:req];
}

#pragma clang diagnostic pop

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