iOS对静态库的网络请求函数进行hook

问题

要对第三方厂商SDK的.a静态库中某些网络请求进行替换操作

解决方案

1. 因为第三方厂商SDK中的网络请求框架不对外开放，所以通过对.a库使用Hopper Disassembler进行分析，定位到是使用什么函数进行请求

2. 建立一个方法，对.a中的网络框架方法进行swizzling

   Class systemClass = NSClassFromString(@"XXXNetURLSessionManager");
    
    SEL sel_System = @selector(dataTaskWithRequest:uploadProgress:downloadProgress:completionHandler:);
    SEL sel_Custom = @selector(hook_dataTaskWithRequest:uploadProgress:downloadProgress:completionHandler:);
    
    Method method_System = class_getInstanceMethod(systemClass, sel_System);
    Method method_Custom = class_getInstanceMethod([self class], sel_Custom);
    
    IMP imp_System = method_getImplementation(method_System);
    IMP imp_Custom = method_getImplementation(method_Custom);
    
    if (class_addMethod(systemClass, sel_Custom, imp_System, method_getTypeEncoding(method_System))) {
        class_replaceMethod(systemClass, sel_System, imp_Custom, method_getTypeEncoding(method_System));
    } else {
        method_exchangeImplementations(method_System, method_Custom);
    }

3. 在hook方法中，通过GCD，发起自身的网络请求，等返回结果后进行参数映射后再return

- (NSURLSessionDataTask *)hook_dataTaskWithRequest:(NSURLRequest *)request uploadProgress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock downloadProgress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler {
    // 创建一个信号量
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);

    // 异步操作
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 在这里执行您的异步操作，比如网络请求
        // 当异步操作完成后，调用 completionHandler 返回结果
        
        // 假设您的异步操作是一个网络请求
        NSURLSessionDataTask *dataTask = [NSURLSession.sharedSession dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
            // 处理异步操作的结果
            // ...
            
            // 调用 completionHandler 返回结果
            completionHandler(response, responseObject, error);
            
            // 发送信号，解除阻塞
            dispatch_semaphore_signal(semaphore);
        }];
        
        [dataTask resume];
    });

    // 阻塞当前线程，等待信号
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);

    // 返回结果
    return [self hook_dataTaskWithRequest:request uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];
}