# AssetsLibrary Constants ## Topics ### Constants [`extern NSString * const ALAssetLibraryDeletedAssetGroupsKey;`](/documentation/AssetsLibrary/ALAssetLibraryDeletedAssetGroupsKey) Value is a set of objects identifying the asset groups that were deleted. [`extern NSString * const ALAssetLibraryInsertedAssetGroupsKey;`](/documentation/AssetsLibrary/ALAssetLibraryInsertedAssetGroupsKey) Value is a set of objects identifying the assets that were inserted. [`extern NSString * const ALAssetLibraryUpdatedAssetGroupsKey;`](/documentation/AssetsLibrary/ALAssetLibraryUpdatedAssetGroupsKey) Value is a set of objects identifying the asset groups that were updated. [`extern NSString * const ALAssetLibraryUpdatedAssetsKey;`](/documentation/AssetsLibrary/ALAssetLibraryUpdatedAssetsKey) Value is a set of objects identifying the assets that were updated. [`extern NSString * const ALAssetPropertyAssetURL;`](/documentation/AssetsLibrary/ALAssetPropertyAssetURL) The key to retrieve a URL identifier for the asset. [`extern NSString * const ALAssetPropertyDate;`](/documentation/AssetsLibrary/ALAssetPropertyDate) The key to retrieve the creation date of the asset. [`extern NSString * const ALAssetPropertyDuration;`](/documentation/AssetsLibrary/ALAssetPropertyDuration) The key to retrieve the play time duration of a video asset. [`extern NSString * const ALAssetPropertyLocation;`](/documentation/AssetsLibrary/ALAssetPropertyLocation) The key to retrieve the location information of the asset. [`extern NSString * const ALAssetPropertyOrientation;`](/documentation/AssetsLibrary/ALAssetPropertyOrientation) The key to retrieve the orientation of the asset. [`extern NSString * const ALAssetPropertyRepresentations;`](/documentation/AssetsLibrary/ALAssetPropertyRepresentations) The key to retrieve the representations available for a given asset (for example RAW, JPEG). [`extern NSString * const ALAssetPropertyType;`](/documentation/AssetsLibrary/ALAssetPropertyType) A key to retrieve the type of the asset. [`extern NSString * const ALAssetPropertyURLs;`](/documentation/AssetsLibrary/ALAssetPropertyURLs) The key to retrieve a dictionary that maps asset representations UTIs to URLs that uniquely identify the asset. [`extern NSString * const ALAssetTypePhoto;`](/documentation/AssetsLibrary/ALAssetTypePhoto) Specifies that the asset is a photo. [`extern NSString * const ALAssetTypeUnknown;`](/documentation/AssetsLibrary/ALAssetTypeUnknown) Specifies that the asset’s type cannot be determined. [`extern NSString * const ALAssetTypeVideo;`](/documentation/AssetsLibrary/ALAssetTypeVideo) Specifies that the asset is a video. [`extern NSString * const ALAssetsGroupPropertyName;`](/documentation/AssetsLibrary/ALAssetsGroupPropertyName) Key to retrieve the name of the group. [`extern NSString * const ALAssetsGroupPropertyPersistentID;`](/documentation/AssetsLibrary/ALAssetsGroupPropertyPersistentID) Key to retrieve the group’s persistent ID. [`extern NSString * const ALAssetsGroupPropertyType;`](/documentation/AssetsLibrary/ALAssetsGroupPropertyType) Key to retrieve the group type. [`extern NSString * const ALAssetsGroupPropertyURL;`](/documentation/AssetsLibrary/ALAssetsGroupPropertyURL) Key to retrieve a URL that uniquely identifies the group. [`extern NSString * const ALAssetsLibraryChangedNotification;`](/documentation/AssetsLibrary/ALAssetsLibraryChangedNotification) Sent when the contents of the assets library have changed from under the app that is using the data. [`extern NSString * const ALAssetsLibraryErrorDomain;`](/documentation/AssetsLibrary/ALAssetsLibraryErrorDomain) Constant used by to distinguish errors belonging to the AssetsLibrary domain. [`extern NSString * const ALErrorInvalidProperty;`](/documentation/AssetsLibrary/ALErrorInvalidProperty) Value returned by `ALAsset/value(forProperty:)` if the property you tried to access is invalid. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)