使用ALAssetLibrary获取照片库中图像的时间戳

我正在尝试显示图片库中的图像以及时间戳（创build或修改的时间）。 我已经使用下面的代码获取图像。 我怎样才能正确地得到他们的时间戳？ 这里是代码：

-(void)getAllPictures{ imageArray=[[NSArray alloc] init]; mutableArray =[[NSMutableArray alloc]init]; NSMutableArray* assetURLDictionaries = [[NSMutableArray alloc] init]; library = [[ALAssetsLibrary alloc] init]; void (^assetEnumerator)( ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop) { if(result != nil) { if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) { [assetURLDictionaries addObject:[result valueForProperty:ALAssetPropertyURLs]]; NSURL *url= (NSURL*) [[result defaultRepresentation]url]; [library assetForURL:url resultBlock:^(ALAsset *asset) { [mutableArray addObject:[UIImage imageWithCGImage:[[asset defaultRepresentation] fullScreenImage]]]; if ([mutableArray count]==count) { imageArray=[[NSArray alloc] initWithArray:mutableArray]; [self allPhotosCollected:imageArray]; } } failureBlock:^(NSError *error){ NSLog(@"operation was not successfull!"); } ]; NSLog(@"ali: %@",result); } } }; NSMutableArray *assetGroups = [[NSMutableArray alloc] init]; void (^ assetGroupEnumerator) ( ALAssetsGroup *, BOOL *)= ^(ALAssetsGroup *group, BOOL *stop) { if(group != nil) { [group enumerateAssetsUsingBlock:assetEnumerator]; [assetGroups addObject:group]; count=[group numberOfAssets]; } }; assetGroups = [[NSMutableArray alloc] init]; [library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:assetGroupEnumerator failureBlock:^(NSError *error) {NSLog(@"There is an error");}];} -(void)allPhotosCollected:(NSArray*)imgArray{ //write your code here after getting all the photos from library... NSLog(@"all pictures are %@",imgArray); for (int i=0; i<imgArray.count; i++) { UIImageView *img=[[UIImageView alloc] initWithImage:imgArray[i]]; img.frame=CGRectMake(10, 20+105*i, 200, 100); [self.view addSubview:img]; } 

}

Answer 1

获得时间戳使用这个：

  NSDate *date = [asset valueForProperty:ALAssetPropertyDate];