脸书照片下载

Question

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.

Answer 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。