Question

我无法从Flickr有效下载照片数量。我用过了主队列。但这还不够。打击是我的代码。

-(void)flickrNewPhotosFromArray:(NSArray *)photos withCompletionHandler: (void (^) (NSArray*))completionHandler{
    dispatch_queue_t fetchQ = dispatch_queue_create("fetch photos1", NULL);
    dispatch_async(fetchQ, ^{

        NSMutableArray *arrayPhotos = [[NSMutableArray alloc] init];

        for(int i = 0; i < photos.count; i ++){
            NSMutableDictionary *mutableDict = [[NSMutableDictionary alloc] init];
            NSURL *url = [FlickrFetcher URLforPhoto:photos[i] format:FlickrPhotoFormatLarge];
            NSString *urlString = [url absoluteString];
            NSData * data = [[NSData alloc] initWithContentsOfURL:url];
            UIImage *image = [[UIImage alloc] initWithData:data];
            CGFloat width = image.size.width;
            CGFloat height = image.size.height;
            [mutableDict setObject:urlString forKey:@"img"];
            [mutableDict setObject:[NSNumber numberWithInt:width] forKey:@"w"];
            [mutableDict setObject:[NSNumber numberWithInt:height] forKey:@"h"];
            [arrayPhotos addObject:mutableDict];
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            if (completionHandler) {
                completionHandler(arrayPhotos);
            }
        });
    });
}

我需要检查图像的宽度和高度以满足水流收集视图的要求，因为我下载的字典不提供这些。感谢您的帮助。

Answer 1

我想我自己得到了答案。只需使用组队列来处理！答案如下！仍然欢迎给我建议或提供更好的答案！感谢

-(void)flickrNewPhotosFromArray:(NSArray *)photos withCompletionHandler: (void (^) (NSArray*))completionHandler{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    dispatch_async(queue, ^{
        dispatch_group_t group = dispatch_group_create();

        __block NSMutableArray *arrayPhotos = [[NSMutableArray alloc] init];

        for(int i = 0; i < photos.count; i ++){

            dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

                NSMutableDictionary *mutableDict = [[NSMutableDictionary alloc] init];
                NSURL *url = [FlickrFetcher URLforPhoto:photos[i] format:FlickrPhotoFormatLarge];
                NSString *urlString = [url absoluteString];
                NSData * data = [[NSData alloc] initWithContentsOfURL:url];
                UIImage *image = [[UIImage alloc] initWithData:data];
                CGFloat width = image.size.width;
                CGFloat height = image.size.height;
                [mutableDict setObject:urlString forKey:@"img"];
                [mutableDict setObject:[NSNumber numberWithInt:width] forKey:@"w"];
                [mutableDict setObject:[NSNumber numberWithInt:height] forKey:@"h"];
                [arrayPhotos addObject:mutableDict];

            });
        }
        dispatch_group_notify(group, dispatch_get_main_queue(), ^{
            if (completionHandler) {
                completionHandler(arrayPhotos);
            }
        });
    });
}

iOS - 如何从Flickr下载大量照片

1 个答案: