iphone – NSURLCache没有缓存

所以我已经子类化NSURLCache并且每次调用load HTMLFromString时:它调用storeCachedRequest:forRequest:然后调用cachedResponseForRequest:.这就是我所拥有的:

- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
{
    NSString *pathString = [[request URL] absoluteString];

    NSCachedURLResponse * response = [super cachedResponseForRequest:request];
    if (response != nil)
        return response;
    else {
        NSString* myString= @"testing";

        NSData* data=[myString dataUsingEncoding: NSASCIIStringEncoding ];

        //
        // Create the cacheable response
        //
        NSURLResponse *response =
        [[[NSURLResponse alloc]
          initWithURL:[request URL]
          MIMEType:[self mimeTypeForPath:pathString]
          expectedContentLength:[data length]
          textEncodingName:nil]
         autorelease];
        NSCachedURLResponse * cachedResponse =
        [[[NSCachedURLResponse alloc] initWithResponse:response data:data] autorelease];

        [self storeCachedResponse:cachedResponse forRequest:request] ;

        //NSLog(@"DEFAULT CACHE WITH URL %@", [[request URL] absoluteString]);
        return [super cachedResponseForRequest:request];
    }

    return nil;
}

- (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NSURLRequest *)request
{
    [super storeCachedResponse:cachedResponse forRequest:request];

    NSLog(@"STORE CACHED RESPONSE WITH URL %@", [[request URL] absoluteString]);
}

问题是当我调用cachedResponseForRequest时:在保存之后,响应总是为零.为什么是这样?

我有:

NSURLRequest * req = [NSURLRequest requestWithURL:[NSURL URLWithString:self.imageSource_]];
NSCachedURLResponse * response = [[NSURLCache sharedURLCache] cachedResponseForRequest:req];

if (response == nil)
    NSLog(@"RESPONSE IS NIL");
else {
    NSString* theString = [[NSString alloc] initWithData:response.data encoding:NSASCIIStringEncoding];
    NSLog(@"RESPONSE IS NOT NIL %@", theString);
}

并且它总是打印响应为零. url字符串与它时的字符串相同
storeCachedResponse.出于某种原因,它不是缓存.我已将缓存大小设置为一定的大小.

不是100%肯定,但我认为您需要使用NSURLConnection返回的NSURLResponse而不是创建自己的NSURLResponse.我怀疑如果您只是创建一个NSURLResponse,它没有为缓存设置任何标头,因此NSURLCache假定它应该缓存此特定结果.
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