一、缓存图片

//1.首先创建在沙盒中创建一个文件夹用于保存图片

 

NSFileManager *fileManager = [[NSFileManager alloc] init];

    NSString *pathDocuments = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    NSString *createPath = [NSString stringWithFormat:@"%@/Image", pathDocuments];

    

    // 判断文件夹是否存在，如果不存在，则创建

    if (![[NSFileManager defaultManager] fileExistsAtPath:createPath]) {

        [fileManager createDirectoryAtPath:createPath withIntermediateDirectories:YES attributes:nil error:nil];

    } else {

        NSLog(@"FileDir is exists.");

    }

    

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

        UIImageView * imageV = [[UIImageView alloc]initWithFrame:CGRectMake(screenWidth * i, 0, screenWidth, self.homePageview.height)];

        [imageV sd_setImageWithURL:[viewsArray objectAtIndex:i]placeholderImage:[UIImage imageNamed:@"Moren6p.png"]];

        UITapGestureRecognizer * tap =[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapAction:)];

        [imageV addGestureRecognizer:tap];

        imageV.userInteractionEnabled = YES;

        [self.homePageview addSubview:imageV];

        

        UIImage * image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[viewsArray objectAtIndex:i]]];

        

//2.缓存我所需要的图片

        NSString *path_sandox = NSHomeDirectory();

        //创建路径

        NSString *CachePath = [NSString stringWithFormat:@"/Documents/Image/HomeScroll%d.png",i];

        //设置一个图片的存储路径

        NSString *imagePath = [path_sandox stringByAppendingString:CachePath];

        //把图片直接保存到指定的路径（同时应该把图片的路径imagePath存起来，下次就可以直接用来取）

        [UIImagePNGRepresentation(image) writeToFile:imagePath atomically:YES];

        

    }

 

二、读取图片

 

//1.首先获取沙盒路径

         NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

        NSString *documentsDirectory = [paths objectAtIndex:0];

        NSFileManager *fileManage = [NSFileManager defaultManager];

        NSString *CacheDocuments = [documentsDirectory stringByAppendingPathComponent:@"/Image”];//我把图片缓存到沙盒中的Document下得Image文件夹中

        NSArray *CacheScrollImage = [fileManage subpathsOfDirectoryAtPath:CacheDocuments error:nil];//这个是获取Image文件夹下所有文件的文件名数组

 

//2.离线加载沙盒中缓存的图片

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

            NSString * CacheImage = [NSString stringWithFormat:@"Image/HomeScroll%d.png",i];

            NSString *myDirectory = [documentsDirectory stringByAppendingPathComponent:CacheImage];

            NSData *data = [fileManage contentsAtPath:myDirectory];

            UIImage * image = [UIImage imageWithData:data];

        }