【iOS开发】---- 快速将大图保存到本地

来源：互联网发布：three.js 全景图编辑：程序博客网时间：2024/05/21 22:51

碰到一个问题：如何快速的批量保存iphone相册中的图片（原始的大图，分辨率高）到本地？

保存图片到本地，首先得拿到这个图片：alAsset.defaultRepresentation.fullResolutionImage.但是图片太大了，大批量的保存取这个图片就得花很长的时间，再转NSData存入本地又得很久，所以这种读写方式是不行的。

我google了一下，在stack overflow找到了方法：点击打开链接。

我把实现的方法贴一下（包括大图和缩略图）：

//reading out the orginal images    for (int j=0; j<[assetArray count]; j++) {    ALAssetRepresentation *representation = [[assetArray objectAtIndex:j] defaultRepresentation];    NSString* filename = [documentPath stringByAppendingPathComponent:[representation filename]];    [[NSFileManager defaultManager] createFileAtPath:filename contents:nil attributes:nil];    NSOutputStream *outPutStream = [NSOutputStream outputStreamToFileAtPath:filename append:YES];    [outPutStream open];    long long offset = 0;    long long bytesRead = 0;    NSError *error;    uint8_t * buffer = malloc(131072);    while (offset<[representation size] && [outPutStream hasSpaceAvailable]) {        bytesRead = [representation getBytes:buffer fromOffset:offset length:131072 error:&error];        [outPutStream write:buffer maxLength:bytesRead];        offset = offset+bytesRead;    }    [outPutStream close];    free(buffer);}//reading out the fullScreenImages and thumbnailsfor (int j=0; j<[assetArray count]; j++) {    @autoreleasepool    {        ALAsset *asset = [assetArray objectAtIndex:j];         NSString *orgFilename = [representation filename];         NSString *filenameFullScreen = [NSString stringWithFormat:@"%@_fullscreen.png",[orgFilename stringByDeletingPathExtension]]         NSString* pathFullScreen = [documentPath stringByAppendingPathComponent:filenameFullScreen];         CGImageRef imageRefFullScreen = [[asset defaultRepresentation] fullScreenImage];         UIImage *imageFullScreen = [UIImage imageWithCGImage:imageRefFullScreen];         NSData *imageDataFullScreen = UIImagePNGRepresentation(imageFullScreen);         [imageDataFullScreen writeToFile:pathFullScreen atomically:YES];         NSString *filenameThumb = [NSString stringWithFormat:@"%@_thumb.png",[orgFilename stringByDeletingPathExtension]]         NSString* pathThumb = [documentPath stringByAppendingPathComponent:filenameThumb];         CGImageRef imageRefThumb = [asset thumbnail];         UIImage *imageThumb = [UIImage imageWithCGImage:imageRefThumb];         NSData *imageDataThumb = UIImagePNGRepresentation(imageThumb);         [imageDataThumb writeToFile:pathThumb atomically:YES];    }}

参考：http://stackoverflow.com/questions/9973259/what-is-the-correct-way-to-import-save-photos-from-iphone-album