ALAssetsLibrary Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/AssetsLibrary.framework
Availability
Available in iOS 4.0 and later.
Declared in
ALAssetsLibrary.h
Related sample code

Overview

An instance of ALAssetsLibrary provides access to the videos and photos that are under the control of the Photos application.

The library includes those that are in the Saved Photos album, those coming from iTunes, and those that were directly imported into the device. You use it to retrieve the list of all asset groups and to save images and videos into the Saved Photos album.

You create an instance of ALAssetsLibrary using alloc and init:

ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];

The lifetimes of objects you get back from a library instance are tied to the lifetime of the library instance.

Many of the methods declared by ALAssetsLibrary take blocks for failure and success as arguments. These methods are all asynchronous because the user may need to be asked to grant access to the data.

Tasks

Accessing Assets

Managing Notifications

Finding Assets

Enumerating Assets

Saving Assets

Managing Asset Groups

Class Methods

authorizationStatus

Returns photo data authorization status for this application.

+ (ALAuthorizationStatus)authorizationStatus
Return Value

Photo data authorization status for this application. For the constants returned, see “ALAuthorizationStatus.”

Discussion

This method does not prompt the user for access.

You can use it to detect restricted access and simply hide UI instead of prompting for access.

Availability
  • Available in iOS 6.0 and later.
Declared In
ALAssetsLibrary.h

disableSharedPhotoStreamsSupport

Disables shared photo streams notifications and asset retrieval.

+ (void)disableSharedPhotoStreamsSupport
Discussion

Shared photo streams can generate frequent notifications. Use this method to disable support if appropriate for your app.

Apps compiled against versions of iOS prior to iOS 6.0 do not have support for shared photo streams.

Availability
  • Available in iOS 6.0 and later.
Declared In
ALAssetsLibrary.h

Instance Methods

addAssetsGroupAlbumWithName:resultBlock:failureBlock:

Adds a new assets group to the library.

- (void)addAssetsGroupAlbumWithName:(NSString *)name resultBlock:(ALAssetsLibraryGroupResultBlock)resultBlock failureBlock:(ALAssetsLibraryAccessFailureBlock)failureBlock
Parameters
name

The name for the new group.

If name conflicts with another assets group with the same name, then the group is not created and resultBlock returns a nil group.

resultBlock

The block invoked after the add operation completes.

For a description of the block, see ALAssetsLibraryAccessFailureBlock.

failureBlock

The block to invoke if the add operation fails—for example, if the user denies access to the application.

For a description of the block, see ALAssetsGroupFaces.

Discussion

The name of the new asset group is name, its type is ALAssetsGroupAlbum, and the editable property is YES.

This method is asynchronous. When the assets group is added, the user may be asked to confirm the application’s access to the data; the method, though, returns immediately. You should perform whatever work you want with the group in resultBlock.

If the user denies access to the application, or if no application is allowed to access the data, or if the data is currently unavailable, the failure block is called.

Availability
  • Available in iOS 5.0 and later.
Declared In
ALAssetsLibrary.h

assetForURL:resultBlock:failureBlock:

Invokes a given block passing as a parameter an asset identified by a specified file URL.

- (void)assetForURL:(NSURL *)assetURL resultBlock:(ALAssetsLibraryAssetForURLResultBlock)resultBlock failureBlock:(ALAssetsLibraryAccessFailureBlock)failureBlock
Parameters
assetURL

An asset URL previously retrieved from an ALAsset object.

resultBlock

The block to invoke using the asset identified by assetURL.

For a description of the block, see ALAssetsLibraryAssetForURLResultBlock.

failureBlock

The block to invoke if the user denies access to the assets library.

For a description of the block, see ALAssetsLibraryAccessFailureBlock.

Discussion

This method is asynchronous. When the asset is requested, the user may be asked to confirm the application's access to the library; the method, though, returns immediately. You should perform whatever work you want with the asset in resultBlock.

If the user denies access to the application, or if no application is allowed to access the data, the failure block is called.

Availability
  • Available in iOS 4.0 and later.
Related Sample Code
Declared In
ALAssetsLibrary.h

enumerateGroupsWithTypes:usingBlock:failureBlock:

Invokes a given block passing as a parameter each of the asset groups that match the given asset group type.

- (void)enumerateGroupsWithTypes:(ALAssetsGroupType)types usingBlock:(ALAssetsLibraryGroupsEnumerationResultsBlock)enumerationBlock failureBlock:(ALAssetsLibraryAccessFailureBlock)failureBlock
Parameters
types

The types of asset group over which to enumerate.

The value is a bitfield; you can OR together values from writeImageDataToSavedPhotosAlbum:metadata:completionBlock:.

enumerationBlock

The block to invoke using each asset group in turn.

When the enumeration is done, enumerationBlock is invoked with group set to nil.

For a description of the block, see ALAssetsLibraryGroupsEnumerationResultsBlock.

failureBlock

The block to invoke if the user denies access to the assets library.

For a description of the block, see ALAssetsLibraryAccessFailureBlock.

Discussion

The results are passed one by one to the caller by executing the enumeration block.

This method is asynchronous. When groups are enumerated, the user may be asked to confirm the application's access to the data; the method, though, returns immediately. You should perform whatever work you want with the assets in enumerationBlock.

If the user denies access to the application, or if no application is allowed to access the data, the failureBlock is called.

Special Considerations

This method will fail with error ALAssetsLibraryAccessGloballyDeniedError if the user has not enabled Location Services (in Settings > General).

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

groupForURL:resultBlock:failureBlock:

Returns an assets group in the result block for a URL previously retrieved from an ALAssetsGroup object.

- (void)groupForURL:(NSURL *)groupURL resultBlock:(ALAssetsLibraryGroupResultBlock)resultBlock failureBlock:(ALAssetsLibraryAccessFailureBlock)failureBlock
Parameters
groupURL

The URL for an ALAssetsGroup object.

resultBlock

The block invoked after the access operation completes.

For a description of the block, see ALAssetsLibraryAccessFailureBlock.

failureBlock

The block to invoke if the access operation fails—for example, if the user denies access to the application.

For a description of the block, see ALAssetsGroupFaces.

Discussion

This method is asynchronous: it returns immediately. You should perform whatever work you want with the assets group in resultBlock.

This method is asynchronous. When the assets group is requested, the user may be asked to confirm the application’s access to the data; the method, though, returns immediately. You should perform whatever work you want with the asset group in resultBlock.

If the user denies access to the application, or if no application is allowed to access the data, or if the data is currently unavailable, the failure block is called.

Availability
  • Available in iOS 5.0 and later.
Declared In
ALAssetsLibrary.h

videoAtPathIsCompatibleWithSavedPhotosAlbum:

Returns a Boolean value that indicates whether a video identified by a given URL is compatible with the Saved Photos album.

- (BOOL)videoAtPathIsCompatibleWithSavedPhotosAlbum:(NSURL *)videoPathURL
Parameters
videoPathURL

An URL that points to a video file.

Return Value

YES if the video identified by videoPathURL is compatible with the Saved Photos album, otherwise NO.

Discussion

This method returns the same value as UIVideoAtPathIsCompatibleWithSavedPhotosAlbum would for the same URL.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

writeImageDataToSavedPhotosAlbum:metadata:completionBlock:

Writes given image data and metadata to the Photos Album.

- (void)writeImageDataToSavedPhotosAlbum:(NSData *)imageData metadata:(NSDictionary *)metadata completionBlock:(ALAssetsLibraryWriteImageCompletionBlock)completionBlock
Parameters
imageData

Data for the image to add to the album.

metadata

The metadata to associate with the image.

completionBlock

The block invoked after the save operation completes.

For a description of the block, see ALAssetsLibraryWriteImageCompletionBlock.

Discussion

If there is a conflict between the metadata in the image data and the metadata dictionary, the image data metadata values will be overwritten.

Availability
  • Available in iOS 4.1 and later.
Related Sample Code
Declared In
ALAssetsLibrary.h

writeImageToSavedPhotosAlbum:metadata:completionBlock:

Writes a given image and metadata to the Photos Album.

- (void)writeImageToSavedPhotosAlbum:(CGImageRef)imageRef metadata:(NSDictionary *)metadata completionBlock:(ALAssetsLibraryWriteImageCompletionBlock)completionBlock
Parameters
imageRef

The image to add to the album.

metadata

The metadata to associate with the image.

completionBlock

The block invoked after the save operation completes.

For a description of the block, see ALAssetsLibraryWriteImageCompletionBlock.

Discussion

You must specify the orientation key in the metadata dictionary to preserve the orientation of the image.

Availability
  • Available in iOS 4.1 and later.
Declared In
ALAssetsLibrary.h

writeImageToSavedPhotosAlbum:orientation:completionBlock:

Saves a given image to the Saved Photos album.

- (void)writeImageToSavedPhotosAlbum:(CGImageRef)imageRef orientation:(ALAssetOrientation)orientation completionBlock:(ALAssetsLibraryWriteImageCompletionBlock)completionBlock
Parameters
imageRef

The image to save to the Saved Photos album.

orientation

The orientation at which to save the image.

completionBlock

The block invoked after the save operation completes.

For a description of the block, see ALAssetsLibraryWriteImageCompletionBlock.

Discussion

If you want to save a UIImage object, you can use the UIImage method CGImage to get a CGImageRef, and cast the image’s imageOrientation to ALAssetOrientation.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

writeVideoAtPathToSavedPhotosAlbum:completionBlock:

Saves a video identified by a given URL to the Saved Photos album.

- (void)writeVideoAtPathToSavedPhotosAlbum:(NSURL *)videoPathURL completionBlock:(ALAssetsLibraryWriteVideoCompletionBlock)completionBlock
Parameters
videoPathURL

An URL that points to a video file.

completionBlock

The block invoked after the save operation completes.

For a description of the block, see ALAssetsLibraryWriteVideoCompletionBlock.

Discussion

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

Constants

ALAssetsGroupType

A bitfield to identify types of asset.

typedef NSUInteger ALAssetsGroupType;
Discussion

For possible values, see “Types of Asset.”

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

Types of Asset

Constants to identify types of asset.

enum {
   ALAssetsGroupLibrary        = (1 << 0),
   ALAssetsGroupAlbum          = (1 << 1),
   ALAssetsGroupEvent          = (1 << 2),
   ALAssetsGroupFaces          = (1 << 3),
   ALAssetsGroupSavedPhotos    = (1 << 4),
   ALAssetsGroupPhotoStream    = (1 << 5),
   ALAssetsGroupAll            = 0xFFFFFFFF,
};
Constants
ALAssetsGroupLibrary

The Library group that includes all assets that are synced from iTunes.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupAlbum

All the albums created on the device or synced from iTunes, not including Photo Stream or Shared Streams

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupEvent

All events, including those created during Camera Connection Kit import.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupFaces

All the faces albums synced from iTunes.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupSavedPhotos

All the photos in the Camera Roll.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupPhotoStream

The PhotoStream album.

In iOS 6.0 and later, this also includes Shared Streams.

Available in iOS 5.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsGroupAll

The same as ORing together all the group types except for ALAssetsGroupLibrary.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientation

Constants to indicate the orientation of an asset.

typedef enum {
   ALAssetOrientationUp,
   ALAssetOrientationDown,
   ALAssetOrientationLeft,
   ALAssetOrientationRight,
   ALAssetOrientationUpMirrored,
   ALAssetOrientationDownMirrored,
   ALAssetOrientationLeftMirrored,
   ALAssetOrientationRightMirrored,
} ALAssetOrientation;
Constants
ALAssetOrientationUp

Indicates that the picture is in its default orientation, as shown here.../Art/UIImageOrientationUp.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationDown

Indicates that the picture has been rotated through 180 degrees with respect to ALAssetOrientationUp, as shown here.../Art/UIImageOrientationDown.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationLeft

Indicates that the picture has been rotated through 90 degrees counter-clockwise with respect to ALAssetOrientationUp, as shown here.../Art/UIImageOrientationLeft.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationRight

Indicates that the picture has been rotated through 90 degrees clockwise with respect to ALAssetOrientationUp, as shown here.../Art/UIImageOrientationRight.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationUpMirrored

Indicates that the picture has been flipped horizontally with respect to ALAssetOrientationUp, as shown here.../Art/UIImageOrientationUpMirrored.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationDownMirrored

Indicates that the picture has been rotated through 180 degrees with respect to ALAssetOrientationUp and then flipped horizontally, as shown here.../Art/UIImageOrientationDownMirrored.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationLeftMirrored

Indicates that the picture has been rotated through 90 degrees counter-clockwise with respect to ALAssetOrientationUp and then flipped vertically, as shown here.../Art/UIImageOrientationLeftMirrored.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetOrientationRightMirrored

Indicates that the picture has been rotated through 90 degrees clockwise with respect to ALAssetOrientationUp and then flipped vertically, as shown here.../Art/UIImageOrientationRightMirrored.jpg

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryGroupsEnumerationResultsBlock

Signature for the block executed when a match is found during enumeration using enumerateGroupsWithTypes:usingBlock:failureBlock:.

typedef void (^ALAssetsLibraryGroupsEnumerationResultsBlock)(ALAssetsGroup *group, BOOL *stop);
Discussion

The block parameters are defined as follows:

group

The current asset group in the enumeration.

stop

A pointer to a boolean value; set the value to YES to stop enumeration.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

ALAssetsLibraryAssetForURLResultBlock

Signature for the block executed if the user has granted access to the caller to access the data managed by the framework in assetForURL:resultBlock:failureBlock:.

typedef void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *asset);
Discussion

The block parameter is defined as follows:

asset

The asset identified by the URL parameter in assetForURL:resultBlock:failureBlock:.

If the asset is not found, asset is nil.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

ALAssetsLibraryWriteImageCompletionBlock

Signature for the block executed when writeImageToSavedPhotosAlbum:orientation:completionBlock: completes.

typedef void (^ALAssetsLibraryWriteImageCompletionBlock)(NSURL *assetURL, NSError *error);
Discussion

The block parameters are defined as follows:

assetURL

An URL that identifies the saved image file.

If the image is not saved, assetURL is nil.

error

If the image is not saved, an error object that describes the reason for failure, otherwise nil.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

ALAssetsLibraryWriteVideoCompletionBlock

Signature for the block executed when writeVideoAtPathToSavedPhotosAlbum:completionBlock: completes.

typedef void (^ALAssetsLibraryWriteVideoCompletionBlock)(NSURL *assetURL, NSError *error);
Discussion

The block parameters are defined as follows:

assetURL

An URL that identifies the saved video file.

If the video is not saved, assetURL is nil.

error

If the video is not saved, an error object that describes the reason for failure, otherwise nil.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

ALAssetsLibraryAccessFailureBlock

Signature for the block executed if the user does not grant access to the caller to access the data managed by the framework.

typedef void (^ALAssetsLibraryAccessFailureBlock)(NSError *error);
Discussion

The block parameter is defined as follows:

error

An error object that describes why access to the library failed.

This block type is used by assetForURL:resultBlock:failureBlock: and enumerateGroupsWithTypes:usingBlock:failureBlock:.

Availability
  • Available in iOS 4.0 and later.
Declared In
ALAssetsLibrary.h

ALAssetsLibraryGroupResultBlock

Signature for the block executed if the user grants access to the caller to access the data managed by the framework..

typedef void (^ALAssetsLibraryGroupResultBlock)(ALAssetsGroup *group));
Discussion

The block parameter is defined as follows:

group

The group that was added to the assets library.

If the group is not found or not created (for example, because of a name collision), group is nil.

This block type is used by addAssetsGroupAlbumWithName:resultBlock:failureBlock: and groupForURL:resultBlock:failureBlock:.

Availability
  • Available in iOS 5.0 and later.
Declared In
ALAssetsLibrary.h

ALAuthorizationStatus

Constants to indicate authorization status.

typedef NS_ENUM(NSInteger,
   ALAuthorizationStatus) {
   ALAuthorizationStatusNotDetermined = 0,
   ALAuthorizationStatusRestricted,
   ALAuthorizationStatusDenied,
   ALAuthorizationStatusAuthorized };
Constants
ALAuthorizationStatusNotDetermined

User has not yet made a choice with regards to this application.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAuthorizationStatusRestricted

This application is not authorized to access photo data.

The user cannot change this application’s status, possibly due to active restrictions such as parental controls being in place.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAuthorizationStatusDenied

User has explicitly denied this application access to photos data.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAuthorizationStatusAuthorized

User has authorized this application to access photos data.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

Notification Keys

Keys used to get values from the user information dictionary of the ALAssetsLibraryChangedNotification notification.

NSString * const ALAssetLibraryUpdatedAssetsKey;
NSString * const ALAssetLibraryInsertedAssetGroupsKey;
NSString * const ALAssetLibraryUpdatedAssetGroupsKey;
NSString * const ALAssetLibraryDeletedAssetGroupsKey;
Constants
ALAssetLibraryUpdatedAssetsKey

Value is a set of NSURL objects identifying the assets that were updated.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetLibraryInsertedAssetGroupsKey

Value is a set of NSURL objects identifying the assets that were inserted.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetLibraryUpdatedAssetGroupsKey

Value is a set of NSURL objects identifying the asset groups that were updated.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetLibraryDeletedAssetGroupsKey

Value is a set of NSURL objects identifying the asset groups that were deleted.

Available in iOS 6.0 and later.

Declared in ALAssetsLibrary.h.

Discussion

Assets that are modified use the ALAssetLibraryUpdatedAssetsKey key. Assets that are inserted or deleted use the ALAssetLibraryUpdatedAssetGroupsKey key for the asset group that contains the asset.

Assets and asset groups that have no strong references are omitted from the notification’s user information dictionary.

Error Domain

Constant for the AssetsLibrary domain.

NSString *const ALAssetsLibraryErrorDomain;
Constants
ALAssetsLibraryErrorDomain

Constant used by NSError to distinguish errors belonging to the AssetsLibrary domain.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

Error Codes

AssetsLibrary-related error codes

enum {
   ALAssetsLibraryUnknownError =               -1,
   
   ALAssetsLibraryWriteFailedError =           -3300,
   ALAssetsLibraryWriteBusyError =             -3301,
   ALAssetsLibraryWriteInvalidDataError =      -3302,
   ALAssetsLibraryWriteIncompatibleDataError = -3303,
   ALAssetsLibraryWriteDataEncodingError =     -3304,
   ALAssetsLibraryWriteDiskSpaceError =        -3305,
   
   ALAssetsLibraryDataUnavailableError =       -3310,
   
   ALAssetsLibraryAccessUserDeniedError =      -3311,
   ALAssetsLibraryAccessGloballyDeniedError =  -3312,
};
Constants
ALAssetsLibraryUnknownError

The reason for the error is unknown.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteFailedError

The attempt to write data failed.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteBusyError

Writing was already busy when the attempt to write was made.

You should attempt the write again.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteInvalidDataError

The data was invalid.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteIncompatibleDataError

The data contained incompatible data.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteDataEncodingError

The data contained data with the wrong encoding.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryWriteDiskSpaceError

There was not enough space on the disk to write the data.

This error may be returned in the completion block for writeVideoAtPathToSavedPhotosAlbum:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock: as well as the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryDataUnavailableError

The data was not available.

This error may be returned in the ALAssetsLibraryAccessFailureBlock for enumerateGroupsWithTypes:usingBlock:failureBlock: and assetForURL:resultBlock:failureBlock:; and in the completion blocks for writeImageToSavedPhotosAlbum:orientation:completionBlock: and writeImageToSavedPhotosAlbum:orientation:completionBlock:; as well as in the completion selector for UIImageWriteToSavedPhotosAlbum and UISaveVideoAtPathToSavedPhotosAlbum.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryAccessUserDeniedError

The user denied access to the library.

This error may be returned in the ALAssetsLibraryAccessFailureBlock block for enumerateGroupsWithTypes:usingBlock:failureBlock: and assetForURL:resultBlock:failureBlock:.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

ALAssetsLibraryAccessGloballyDeniedError

Access to the library was denied globally.

This error may be returned in the ALAssetsLibraryAccessFailureBlock block for enumerateGroupsWithTypes:usingBlock:failureBlock: and assetForURL:resultBlock:failureBlock:.

Available in iOS 4.0 and later.

Declared in ALAssetsLibrary.h.

Notifications

ALAssetsLibraryChangedNotification

Sent when the contents of the assets library have changed from under the app that is using the data.

In iOS 4.0, the notification’s object is nil. In iOS 4.1 and later, the notification object is the library object that posted the notification.

In iOS 6.0 and later, the user information dictionary describes what changed:

  • If the user information dictionary is nil, reload all assets and asset groups.

  • If the user information dictionary an empty dictionary, there is no need to reload assets and asset groups.

  • If the user information dictionary is not empty, reload the effected assets and asset groups. For the keys used, see “Notification Keys.”

This notification is sent on an arbitrary thread.

Availability
Declared In
ALAssetsLibrary.h