有一些三方多图 返回的图片 格式 

NSArray<UIImage *> *photos

而我们自己图片上传服务器是要转换一下 转成

NSArray< NSData *> *photos 

 NSMutableArray *dataArry = [NSMutableArray array];

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

        UIImage * image =imgArray[i];

        UIGraphicsBeginImageContext(image.size);

        [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];

        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();

        NSData *mydata=UIImageJPEGRepresentation(newImage, 1);

        [dataArry addObject:mydata];

    }

    NSArray *picarry = [[NSArray alloc]initWithArray:dataArry];