workspace_2-wallpaper-2560x1440.jpg

/**
 *  上傳多張圖片
 *
 *  @param imageList image數(shù)組
 *  @param block     block, 返回上傳的圖片數(shù)組
 */
+ (void)uploadTaskImages:(NSArray <UIImage *>*)imageList completeBlock:(void(^)(NSArray *imageNameList, BOOL succ))block;

+ (void)uploadTaskImages:(NSArray <UIImage *>*)imageList completeBlock:(void(^)(NSArray *imageNameList, BOOL succ))block {
    NSMutableArray* resultImageList = [NSMutableArray array];
    for (int i = 0; i < imageList.count; i++) {
//創(chuàng)建一個(gè)數(shù)組, 初始值復(fù)制NSNull進(jìn)行占位.
        [resultImageList addObject:[NSNull null]];
    }
    dispatch_group_t taskGroup = dispatch_group_create();
    dispatch_queue_t serialQueue = dispatch_queue_create("com.jason.gcd", DISPATCH_QUEUE_SERIAL);
//    dispatch_set_target_queue(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), serialQueue);
  //多次提交上傳代碼的方法, imageList.count參數(shù)表示提交的次數(shù)
    dispatch_apply(imageList.count, serialQueue, ^(size_t index) {
        dispatch_group_enter(taskGroup);
//--------------------------上傳的圖片的方法, 此處只需換成自己工程中上傳的方法極即可----------------------------
        [QSMApiTool uploadImg:imageList[index] result:^(NSError *error, id result, BOOL isFromCache, AFHTTPRequestOperation *operation) {
            if (error) {
                AppLog(@"第 -------%d-------- 張圖片上傳失敗: error = %@", (int)index + 1, error);
                dispatch_group_leave(taskGroup);
                block(imageList, NO);
            } else {
                AppLog(@"第 -------%d--------- 張圖片上傳成功: 圖片地址 = %@", (int)index + 1, result);
                @synchronized (resultImageList) {
                    resultImageList[index] = result;
                }
                dispatch_group_leave(taskGroup);
            }
        }];
//--------------------------------------------------------
    });
    dispatch_group_notify(taskGroup, serialQueue, ^{
        //此處要回到主線程
        dispatch_async(dispatch_get_main_queue(), ^{
            block(resultImageList, YES);
        });
    });
}

1. 首先dispatch_group_t taskGroup = dispatch_group_create()
   創(chuàng)建一個(gè)任務(wù)組,在任務(wù)組里面多次提交上傳圖的請求.
2. 需要注意的是, 由于上傳圖片是異步的, dispatch_group_enter()顯式的指明一個(gè)任務(wù)執(zhí)行塊進(jìn)入了這個(gè)組，dispatch_group_leave()顯式表明執(zhí)行塊執(zhí)行完畢，移除出組。這樣才能保證所有的圖片上傳完成之后才會(huì)進(jìn)dispatch_group_notify,否則只要有一個(gè)成功就會(huì)走dispatch_group_notify,顯然這不是我們需要的結(jié)果.
3. 在dispatch_group_notify里面要執(zhí)行回到主線程的方法. 否則刷新UI會(huì)失敗.