自定义NSURLProtocol导致__psynch_mutexwait

Question

我正在继承NSURLProtocol来拦截HTTP请求。

以下是自定义NSURLProtocol类。

+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
    if (NSOrderedSame != [request.URL.scheme caseInsensitiveCompare:@"http"] &&
        NSOrderedSame != [request.URL.scheme caseInsensitiveCompare:@"https"]) {
        return NO;
    }

    if ([NSURLProtocol propertyForKey:kURLProtocolRequestHandledKey inRequest:request] ) {
        return NO;
    }

    return YES;
}

+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request {
    NSMutableURLRequest *mutableReqeust = [request mutableCopy];
    [NSURLProtocol setProperty:@YES forKey:kURLProtocolRequestHandledKey inRequest:mutableReqeust];
    return [mutableReqeust copy];
}

- (void)startLoading {
    self.startDate = [NSDate date];
    self.data = [NSMutableData data];
    self.error = nil;

    self.connection = [[NSURLConnection alloc] initWithRequest:[[self class] canonicalRequestForRequest:self.request] delegate:self startImmediately:YES];
}

- (void)stopLoading {
    [self.connection cancel];
}

#pragma mark - NSURLConnectionDelegate

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    [[self client] URLProtocol:self didFailWithError:error];
    self.error = error;
}

- (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection {
    return YES;
}

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[self client] URLProtocol:self didReceiveAuthenticationChallenge:challenge];
}

- (void)connection:(NSURLConnection *)connection didCancelAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[self client] URLProtocol:self didCancelAuthenticationChallenge:challenge];
}

#pragma mark - NSURLConnectionDataDelegate

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)response {
    if (response != nil){
        _response = response;
        NSMutableURLRequest *redirect = [request mutableCopy];
        redirect.URL = request.URL;
        [NSURLProtocol setProperty:@NO forKey:kURLProtocolRequestHandledKey inRequest:redirect];
        [[self client] URLProtocol:self wasRedirectedToRequest:redirect redirectResponse:response];

        return redirect;
    }
    return request;
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [[self client] URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageAllowed];
    _response = response;
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [[self client] URLProtocol:self didLoadData:data];
    [self.data appendData:data];
}

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
    return cachedResponse;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [[self client] URLProtocolDidFinishLoading:self];
}

- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite {

}

我添加一个UIWebView作为子视图，然后加载一个URL http://ln.clientaccess.10086.cn/shop/optical/Appointment?channel=007&PHONE_NUM=18240235054&AREA_CODE=240&key=4A35774433BA79EB950EDE4B5C4D7121，在控制器被解除后，即使我在webView被解除之前在webView上调用- stopLoading，APP也会被冻结。

这是线程堆栈：

Answer 1

我不认为你想在canonicalRequest中修改请求 - 不要管它。您确实希望在startLoading中修改它，并在对NSURLConnection的新调用中使用修改后的请求，以便您的协议在该调用期间不会再次处理它。

第二件事是重定向实现可能是错误的 - 该方法在两种情况下被调用;一旦发送请求（并且重定向为零）;你希望在那种情况下（你做的）返回请求。第二个是当你真正获得重定向时;你想调用客户端（你是），但是你想要返回nil，以便让客户端实际处理重定向（否则非零返回可以指示已经处理了重定向）。

我不确定其中任何一个会导致问题，但它们是不同的。

我认为与我实施的唯一不同的是startImmediately：YES。这是默认值，因此不应成为问题。也许尝试避免缓存，看看是否有帮助，如果上述两者都没有。或者确保在dealloc中的连接上调用-cancel。

Answer 2

使用startImmediately:NO代替startImmediately:YES将解决此问题。

    if (currentRunLoop && [currentRunLoop currentMode]) {
        self.connection = [[NSURLConnection alloc] initWithRequest:[[self class] canonicalRequestForRequest:self.request] delegate:self startImmediately:NO];
        [self.connection scheduleInRunLoop:currentRunLoop forMode:[[NSRunLoop currentRunLoop] currentMode]];
        [self.connection start];

    } else {
        self.connection = [[NSURLConnection alloc] initWithRequest:[[self class] canonicalRequestForRequest:self.request] delegate:self startImmediately:YES];
    }

有线。有人请告诉我为什么？