ios学习--照片框架详解之二 —— PhotoKit PHAsset应用

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typedef NS_ENUM(NSInteger, PHAssetMediaType) {      PHAssetMediaTypeUnknown = 0 ,      PHAssetMediaTypeImage   = 1 ,      PHAssetMediaTypeVideo   = 2 ,      PHAssetMediaTypeAudio   = 3 , } NS_ENUM_AVAILABLE_IOS(8_0);

一、取只有照片类型的PHAsset

应该设置提取选项，其具有一个属性 predicate ，可用于筛选的视频。下面是一个例子做那件事。

PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];

//set up fetch options, mediaType is image.
PHFetchOptions *options = [[PHFetchOptions alloc] init];
options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
options.predicate = [NSPredicate predicateWithFormat:@"mediaType = %d",PHAssetMediaTypeImage];

for (NSInteger i =0; i < smartAlbums.count; i++) {
    PHAssetCollection *assetCollection = smartAlbums[i];
    PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:options];

    NSLog(@"sub album title is %@, count is %ld", assetCollection.localizedTitle, assetsFetchResult.count);
    if (assetsFetchResult.count > 0) {
        for (PHAsset *asset in assetsFetchResult) {
            //you have got your image type asset.
        }
    }
}

二、something  about获取设备本地音视频

1、检索音视频

 

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PHFetchOptions *allPhotosOptions; @property (nonatomic, strong) PHFetchResult *assetsFetchResults; if (allPhotosOptions == nil) {                    allPhotosOptions = [[PHFetchOptions alloc] init];          allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@ "creationDate" ascending:YES]];      }   self.assetsFetchResults = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:allPhotosOptions];

 

 

其中assetsFetchResults存储了所有的图片信息，PHAssetMediaTypeImage为搜索图片的类型，

2、获取图片UIImage 

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[[PHCachingImageManager defaultManager] requestImageForAsset:asset                                      targetSize:AssetGridThumbnailSize                                     contentMode:PHImageContentModeAspectFill                                         options:nil                                   resultHandler:^(UIImage *result, NSDictionary *info) {                                       // Set the cell's thumbnail image if it's still showing the same asset.                                       if ([cell.representedAssetIdentifier isEqualToString:asset.localIdentifier]) {                                           cell.thumbnailImage = result;                                       }                                   }];

asset为assetsFetchResults中的一个PHAsset，targetSize是获取图片的大小，这个根据你显示的方式设置，如果需要获取图片其他信息比如标题可以采用

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1	[phAsset valueForKey:@ "filename" ];

3、播放视频

 

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-( void )setVideoAsset:(PHAsset *)videoAsset {      _videoAsset = videoAsset;      [[PHImageManager defaultManager] requestPlayerItemForVideo:_videoAsset options:nil resultHandler:^(AVPlayerItem * _Nullable playerItem, NSDictionary * _Nullable info) {          self.currentItem = playerItem;          [self.player replaceCurrentItemWithPlayerItem:self.currentItem];          [self.currentItem addObserver:self forKeyPath:@ "status" options:NSKeyValueObservingOptionNew context:nil];      }]; }

三、 

iOS8开发之 PHAsset 保存图片到相册(相机胶卷) 

请查看以下链接：
http://blog.youkuaiyun.com/jeffasd/article/details/50498907

以及其上下博文

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typedef NS_ENUM(NSInteger, PHAssetMediaType) {      PHAssetMediaTypeUnknown = 0 ,      PHAssetMediaTypeImage   = 1 ,      PHAssetMediaTypeVideo   = 2 ,      PHAssetMediaTypeAudio   = 3 , } NS_ENUM_AVAILABLE_IOS(8_0);