脸书照片下载

Posted 2023-03-11

【中文标题】脸书照片下载

【英文标题】：Facebook Photo Downloading

【发布时间】：2016-08-20 03:29:20

【问题描述】：

我正在尝试从我的应用中的用户下载 Facebook 相册。不幸的是，虽然我确实有一个访问令牌，但我从请求中得到了零张专辑。我没有得到错误，只是得到零。为什么？如果您想查看更多代码或提出更多问题，请提出。请注意，我在当前用户注册时已经授权了他们的 Facebook 权限，并且我已经退出该应用程序并多次打开它（不要认为这会是一个问题，因为我有一个访问令牌..？）

- (void)getAlbums:(OLFacebookAlbumRequestHandler)handler 
if ([FBSDKAccessToken currentAccessToken]) 
    // connection is open, perform the request
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    NSString *graphpath = @"me/albums?limit=100&fields=id,name,count,cover_photo";
    if (self.after) 
        graphPath = [graphPath stringByAppendingFormat:@"&after=%@", self.after];
    

    FBSDKGraphRequest *request = [[FBSDKGraphRequest alloc] initWithGraphPath:graphPath parameters:nil];
    [request startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) 
        [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
        if (self.cancelled) 
            return;
        
        if (error) 
            [OLFacebookAlbumRequest handleFacebookError:error completionHandler:handler];
            return;
        

        NSString *parsingErrorMessage = @"Failed to parse Facebook Response. Please check your internet connectivity and try again.";
        NSError *parsingError = [NSError errorWithDomain:kOLErrorDomainFacebookImagePicker code:kOLErrorCodeFacebookImagePickerBadResponse userInfo:@NSLocalizedDescriptionKey: parsingErrorMessage];
        id data = [result objectForKey:@"data"];
        if (![data isKindOfClass:[NSArray class]]) 
            handler(nil, parsingError, nil);
            return;
        

        NSMutableArray *albums = [[NSMutableArray alloc] init];
        for (id album in data) 
            if (![album isKindOfClass:[NSDictionary class]]) 
                continue;
            

            id albumId     = [album objectForKey:@"id"];
            id photoCount  = [album objectForKey:@"count"];
            id name        = [album objectForKey:@"name"];

            if (!([albumId isKindOfClass:[NSString class]] && [photoCount isKindOfClass:[NSNumber class]]
                   && [name isKindOfClass:[NSString class]])) 
                continue;
            

            OLFacebookAlbum *album = [[OLFacebookAlbum alloc] init];
            album.albumId = albumId;
            album.photoCount = [photoCount unsignedIntegerValue];
            album.name = name;
            album.coverPhotoURL = [NSURL URLWithString:[NSString stringWithFormat:@"https://graph.facebook.com/%@/picture?type=small&access_token=%@", album.albumId, [FBSDKAccessToken currentAccessToken].tokenString]];
            [albums addObject:album];
        

        // get next page cursor
        OLFacebookAlbumRequest *nextPageRequest = nil;
        id paging = [result objectForKey:@"paging"];
        if ([paging isKindOfClass:[NSDictionary class]]) 
            id cursors = [paging objectForKey:@"cursors"];
            id next = [paging objectForKey:@"next"]; // next will be non nil if a next page exists
            if (next && [cursors isKindOfClass:[NSDictionary class]]) 
                id after = [cursors objectForKey:@"after"];
                if ([after isKindOfClass:[NSString class]]) 
                    nextPageRequest = [[OLFacebookAlbumRequest alloc] init];
                    nextPageRequest.after = after;
                
            
        

        handler(albums, nil, nextPageRequest);
    ];

else 
    NSString *message = @"No Facebook user authentication found.";
    handler(nil, [NSError errorWithDomain:kOLErrorDomainFacebookImagePicker code:kOLErrorCodeFacebookImagePickerNoOpenSession userInfo:@NSLocalizedDescriptionKey: message], nil);






//Code for fetching albums...
- (void)loadNextAlbumPage 
self.inProgressRequest = self.albumRequestForNextPage;
self.albumRequestForNextPage = nil;
[self.inProgressRequest getAlbums:^(NSArray/*<OLFacebookAlbum>*/ *albums, NSError *error, OLFacebookAlbumRequest *nextPageRequest) 
    self.inProgressRequest = nil;
    self.loadingIndicator.hidden = YES;
    self.albumRequestForNextPage = nextPageRequest;

    if (error) 
        if (self.parentViewController.isBeingPresented) 
            self.loadingIndicator.hidden = NO;
            self.getAlbumError = error; // delay notification so that delegate can dismiss view controller safely if desired.
         else 
            [self.delegate albumViewController:self didFailWithError:error];
        
        return;
    

    NSMutableArray *paths = [[NSMutableArray alloc] init];
    for (NSUInteger i = 0; i < albums.count; ++i) 
        [paths addObject:[NSIndexPath indexPathForRow:self.albums.count + i inSection:0]];
    

    [self.albums addObjectsFromArray:albums];
    if (self.albums.count == albums.count) 
        // first insert request
        [self.tableView reloadData];
     else 
        [self.tableView insertRowsAtIndexPaths:paths withRowAnimation:UITableViewRowAnimationFade];
    

    if (nextPageRequest) 
        self.tableView.tableFooterView = self.loadingFooter;
     else 
        self.tableView.tableFooterView = nil;
    

];


 //And when they signed up:

[[[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:@ @"fields" : @"id,first_name,photos,picture.width(400).height(400)"]
     startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) 
         if (!error)  //etc etc the method continues.

【问题讨论】：

您是否申请了访问照片的权限（user_photos）？另一个问题是 FB 必须先审核您的请求，然后您的应用才能使用它。 developers.facebook.com/docs/facebook-login/…

否，每次请求不同的权限时都会生成不同的访问令牌。我敢打赌，您的访问令牌没有附加访问用户照片的权限。您是如何请求访问令牌的？

您必须在访问照片之前明确请求 user_photos 权限。

您能否添加您正在执行此类操作的某处的代码快照？这是一个相当简单的修复，您不必排除请求照片。 :) developers.facebook.com/docs/facebook-login/ios#permissions

没错。如果你没有这个，你会需要它。

【参考方案1】：

FB 身份验证将为您提供一组特定权限的唯一access_token。要访问用户照片，您需要请求user_photos permission。使用FBSDKLoginButton 请求权限。

loginButton.readPermissions = @[@"public_profile", @"email", @"user_photos"];

一旦您拥有具有所需权限的访问令牌，请将其保存在本地（在设备上）以供将来重复使用。如果访问代码仍然有效，则无需再次请求。如果它变得无效（如果用户明确撤销了对您应用的权限），请将其发送回登录屏幕。