Question

我是iPhone编程的新手。使用下面的代码，我可以在后台快速和异步地从服务器获取图像。

我想以15张图片的形式下载图片。一旦用户向下滚动，他就可以下载并查看下15个图像。此外，我想卸载并删除不再显示的图像。所以我想分批下载图片，如果有1000张图片，我希望他们下载为0-15,15-30,30-45，...等等。

我该如何实现？

使用Lazyloading或SDWebimage源代码项目，我能够像我说的那样获取图像，但我想以3 * 3缩略图显示图像（意味着我每行要显示3张图像）请告诉我怎么办？像这样。我想要像Android中的通用库这样的lib

  //remote image URLs
        URLs = [[NSMutableArray alloc]init];

              for (NSString *path in latestiamge)
        {

            NSURL *URL = [NSURL URLWithString:path];
            if (URL)
            {
                [URLs addObject:URL];

            }
            else
            {
            }
        }

        self.imageURLs = URLs;

        UISwipeGestureRecognizer* swipeUpGestureRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeUpFrom:)];
        swipeUpGestureRecognizer.direction = UISwipeGestureRecognizerDirectionUp;
        [myScrollView addGestureRecognizer:swipeUpGestureRecognizer];

        float horizontal = 2.0;
        float vertical = 2.0;

        for(int i=0; i<[imageURLs count]; i++)

        {
            if((i%3) == 0 && i!=0)
            {
                horizontal = 5.0;
                vertical = vertical + 100.0 + 5.0;
            }
            CGRect frame;
            frame.size.width=100.0;
            frame.size.height=100.0;
            frame.origin.x=0;
            frame.origin.y=0;
            AsyncImageView *imageView = [[AsyncImageView alloc] initWithFrame:frame];
            imageView.contentMode = UIViewContentModeScaleAspectFill;
            imageView.clipsToBounds = YES;
            imageView.tag = i;
            //load the image
            imageView.imageURL = [imageURLs objectAtIndex:i];

            UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc]
                                                 initWithTarget:self
                                                 action:@selector(actionHandleTapOnImageView:)];
            imageView.userInteractionEnabled = YES;
            [imageView addGestureRecognizer:singleTap];
            [myScrollView addSubview:imageView];

            buttonImage1 = [UIButton buttonWithType:UIButtonTypeCustom];
            [buttonImage1 setFrame:CGRectMake(horizontal, vertical, 100.0, 100.0)];
            [buttonImage1 setTag:i];

            [buttonImage1 setImage:[idURLs objectAtIndex:i] forState:UIControlStateNormal];
            [buttonImage1 setImage:[UIImage imageNamed:@"Overlay.png"] forState:UIControlStateSelected];


            [myScrollView addSubview:buttonImage];

            [buttonImage1 addSubview:imageView];
            [myScrollView addSubview:buttonImage1];


           horizontal = horizontal + 100.0 + 5.0;

        }
        [myScrollView setContentSize:CGSizeMake(320.0, vertical + 3900.0)];

Answer 1

如果您有兴趣了解所有工作背后的概念..请仔细阅读以获得基本的理解：

http://www.raywenderlich.com/4295/multithreading-and-grand-central-dispatch-on-ios-for-beginners-tutorial

http://www.raywenderlich.com/19788/how-to-use-nsoperations-and-nsoperationqueues

如果您只想使用异步加载。我建议你用这个。它基于UIImage。这是非常好的

https://github.com/rs/SDWebImage.git

我建议你调查所有这些并享受乐趣。

如何批量下载和显示图像，而不是一次性全部下载

1 个答案: