objective-c - NSURLProtocol 没有得到完整的 NSURLRequest

Question

问题：我有 NSURLProtocol 的子类，但NSURLRequest返回的+canonicalRequestForRequest:或返回的请求-connection:willSendRequest:redirectResponse:从未传递给我的 URL 协议实例。

详细信息：在我的子类中NSURLProtocol，我实现了+canonicalRequestForRequest:向请求添加 HTTP 标头的方法。标头已成功添加，但-startLoading在我的 URL 协议上调用时，self.request不包含该标头。

此外，当connection:willSendRequest:redirectResponse:在 的委托上调用时，NSURLConnection该方法返回的任何请求也永远不会到达我的 URL 协议实例。

我认为问题在于在initWithRequest:cachedResponse:client:之前调用+canonicalRequestForRequest:或被connection:willSendRequest:redirectResponse:调用，并且来自这两种方法的结果请求在它被alloc/之后永远不会传递给我的 URL 协议实例init。

这是 Apple 的 URL 加载系统中的错误吗？有解决方法吗？难道我做错了什么？

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2014 年 4 月 6 日更新

这是一些示例代码。我设置了 2 个标题：一个在-[APViewController connection:willSendRequest:redirectResponse:]call 中X-WillSendRequestTest，另一个在+[APURLProtocol canonicalRequestForRequest:]. 两者都不是NSURLRequest通过调用self.requestwithin获取的-[APURLProtocol startLoading]。

APViewController.m（NSURLProtocol 的代理）

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)redirectResponse {
    NSLog(@"Will send request: %@", request);

    NSMutableURLRequest *newRequest = [request mutableCopy];

    // This header will not be in self.request when fetched within the -[APURLProtocol start loading] method.
    [newRequest setValue:@"12345" forHTTPHeaderField:@"X-WillSendRequestTest"];

    NSLog(@"New request: %@", newRequest);

    return newRequest;
}

APURL协议.m

@interface APURLProtocol () <NSURLConnectionDelegate, NSURLConnectionDataDelegate>
// Private properties
@property (nonatomic, strong) NSURLConnection *connection;
@end




@implementation APURLProtocol

#pragma mark -
#pragma mark Init methods

- (id)initWithRequest:(NSURLRequest *)request cachedResponse:(NSCachedURLResponse *)cachedResponse client:(id<NSURLProtocolClient>)client {
    NSLog(@"%@", NSStringFromSelector(_cmd));

    if ((self = [super initWithRequest:request cachedResponse:cachedResponse client:client])) {

    }

    return self;
}



#pragma mark -
#pragma mark dealloc

- (void)dealloc {
    NSLog(@"%@", NSStringFromSelector(_cmd));

    [_connection cancel];
}



#pragma mark -
#pragma mark Inherited class methods

+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
    NSLog(@"%@ %@", NSStringFromSelector(_cmd), request);

    id requestIsHandled = [self propertyForKey:kAPURLProtocolHandledRequest inRequest:request];

    if (requestIsHandled == nil
            && ([request.URL.scheme caseInsensitiveCompare:@"http"] == NSOrderedSame
                    || [request.URL.scheme caseInsensitiveCompare:@"https"] == NSOrderedSame
                    || [request.URL.scheme caseInsensitiveCompare:@"ftp"] == NSOrderedSame)) {
                NSLog(@"YES");
                return YES;
            }

    NSLog(@"NO");
    return NO;
}


+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request {
    NSLog(@"%@", NSStringFromSelector(_cmd));

    NSMutableURLRequest *newRequest = [request mutableCopy];
    // This header will not be in self.request when fetched within the -[APURLProtocol start loading] method.
    [newRequest setValue:@"12345" forHTTPHeaderField:@"X-CanonicalRequestTest"];

    return newRequest;
}


+ (BOOL)requestIsCacheEquivalent:(NSURLRequest *)aRequest toRequest:(NSURLRequest *)bRequest {
    NSLog(@"Request is cache equivalent:");
    NSLog(@"Request 1: %@", aRequest);
    NSLog(@"Request 2: %@", bRequest);

    return YES;
}



#pragma mark -
#pragma mark Inherited instance methods

- (void)startLoading {
    NSLog(@"%@. Request: %@", NSStringFromSelector(_cmd), self.request);

    NSMutableURLRequest *newRequest = [[self request] mutableCopy];
    [[self class] setProperty:@"" forKey:kAPURLProtocolHandledRequest inRequest:newRequest];

    [self.connection cancel];

    self.connection = [[NSURLConnection alloc] initWithRequest:newRequest
                                                                                                        delegate:self
                                                                                        startImmediately:YES];
}
@end

NSURLRequest+test.m（类扩展NSURLRequest的描述）

警告：不要在家里这样做。不要使用类别覆盖方法或属性。这仅用于快速调试目的。

@implementation NSURLRequest (test)

- (NSString *)description {
    NSString *dataString = [[NSString alloc] initWithData:self.HTTPBody encoding:NSUTF8StringEncoding];

    return [NSString stringWithFormat:@"%@: %p {URL: %@, Method: %@, Headers: %@, Data: %@",
                    NSStringFromClass([self class]), self, self.URL, self.HTTPMethod, [self allHTTPHeaderFields], dataString];
}

@end