Question

我的应用程序必须从Facebook下载个人资料图片。我写下载图像的代码适用于具有直接链接的图像网址（例如：http://www.mydomain.com/profile_picture.png）

但它会为facebook网址产生错误（例如：http://graph.facebook.com/100000741043402/picture）

以下是代码：

NSURLRequest *imageRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:imageUrl] cachePolicy:NSURLRequestReturnCacheDataDontLoad timeoutInterval:30.0];
    AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:imageRequest
                                                                              imageProcessingBlock:nil
                                                                                         cacheName:@"nscache"
                                                                                           success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image){                                                                                                                                                                                                   profilePicture.image = image;

                                                                                               [profilePicture.layer setBorderColor: [[UIColor colorWithRed:137.0/255.0 green:137.0/255.0 blue:137.0/255.0 alpha:1.0] CGColor]];
                                                                                               [profilePicture.layer setBorderWidth: 2.0];
                                                                                           }
                                                                                           failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){ NSLog(@"%@",[error description]); }
                                          ];
    [operation start];

以下是回复：

Error Domain=NSURLErrorDomain Code=-1008 "resource unavailable" UserInfo=0x97e0ae0 {NSErrorFailingURLStringKey=http://graph.facebook.com/100000741043402/picture, NSErrorFailingURLKey=http://graph.facebook.com/100000741043402/picture, NSLocalizedDescription=resource unavailable, NSUnderlyingError=0xa3559b0 "resource unavailable"}

任何提示/建议都将受到高度赞赏。

Answer 1

如果您使用curl转储整个HTTP会话的标头，您会看到：

$curl -IL http://graph.facebook.com/100000741043402/picture
HTTP/1.1 302 Found
Access-Control-Allow-Origin: *
Cache-Control: private, no-cache, no-store, must-revalidate
Content-Type: image/jpeg
Expires: Sat, 01 Jan 2000 00:00:00 GMT
Location: http://profile.ak.fbcdn.net/hprofile-ak-snc6/186199_100000741043402_1626005174_q.jpg
Pragma: no-cache
X-FB-Rev: 693801
X-FB-Debug: dB4yzLkbQuq46xPMq51wruVSccPCm94U4tePFC/VKoc=
Date: Thu, 13 Dec 2012 07:00:39 GMT
Connection: keep-alive
Content-Length: 0

HTTP/1.1 200 OK
Content-Type: image/jpeg
Content-Length: 3055
Last-Modified: Fri, 01 Jan 2010 00:00:00 GMT
X-Backend: hs478.snc6
X-BlockId: 186199
X-Object-Type: PHOTO_PROFILE
Access-Control-Allow-Origin: *
Cache-Control: max-age=1209600
Expires: Thu, 27 Dec 2012 07:00:40 GMT
Date: Thu, 13 Dec 2012 07:00:40 GMT
Connection: keep-alive

因此，FB会将您重定向到个人资料图片，但NSURLRequest不会自动跟踪重定向。 This post (Handling redirects correctly with NSURLConnection)显示了如何处理此问题，主要教训是您必须遵循重定向，直到最终得到指示终端网址的200响应。

AFImageRequestOperation产生错误

1 个答案: