ALAssetsLibrary类是代表系统中整个资源库，使用它可以访问资源库中的资源和保存照片，视频等功能。
_library = [[ALAssetsLibrary alloc]init];
//判断当前应用是否能访问相册资源
/*
typedef NS_ENUM(NSInteger, ALAuthorizationStatus) {
ALAuthorizationStatusNotDetermined = 0, 用户尚未做出了选择这个应用程序的问候
ALAuthorizationStatusRestricted, 此应用程序没有被授权访问的照片数据。可能是家长控制权限。
ALAuthorizationStatusDenied, 用户已经明确否认了这一照片数据的应用程序访问.
ALAuthorizationStatusAuthorized 用户已授权应用访问照片数据.
}
*/
int author = [ALAssetsLibrary authorizationStatus];
NSLog(@"author type:%d",author);
//关闭监听共享照片流产生的频繁通知信息
[ALAssetsLibrary disableSharedPhotoStreamsSupport];
//创建一个相册到相册资源中，并通过block返回创建成功的相册ALAssetsGroup
[_library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) {
//NSString *const ALAssetsGroupPropertyName;
//NSString *const ALAssetsGroupPropertyType;
//NSString *const ALAssetsGroupPropertyPersistentID;
//NSString *const ALAssetsGroupPropertyURL;
//查看相册的名字
NSLog(@"ALAssetsGroupPropertyName:%@",[group valueForProperty:ALAssetsGroupPropertyName]);
//查看相册的类型
NSLog(@"ALAssetsGroupPropertyType:%@",[group valueForProperty:ALAssetsGroupPropertyType]);
//查看相册的存储id
NSLog(@"ALAssetsGroupPropertyPersistentID:%@",[group valueForProperty:ALAssetsGroupPropertyPersistentID]);
//查看相册存储的位置地址
NSLog(@"ALAssetsGroupPropertyURL:%@",[group valueForProperty:ALAssetsGroupPropertyURL]);
groupURL = [group valueForProperty:ALAssetsGroupPropertyURL];
} failureBlock:^(NSError *error) {
}];
新添加了一个名为test的相册
[NSThread sleepForTimeInterval:0.5];
//通过url地址在相册资源中获取该地址的资源文件ALAsset，有可能是相片或视频
[_library assetForURL:[NSURL URLWithString:@""] resultBlock:^(ALAsset *asset) {
/*
NSString *const ALAssetPropertyType;
NSString *const ALAssetPropertyLocation;
NSString *const ALAssetPropertyDuration;
NSString *const ALAssetPropertyOrientation;
NSString *const ALAssetPropertyDate;
NSString *const ALAssetPropertyRepresentations;
NSString *const ALAssetPropertyURLs;
NSString *const ALAssetPropertyAssetURL;
*/
//查看资源的地理位置信息
NSLog(@"ALAssetPropertyLocation:%@",[asset valueForProperty:ALAssetPropertyLocation]);
//如果资源是视频，查看视频的时长
NSLog(@"ALAssetPropertyDuration:%@",[asset valueForProperty:ALAssetPropertyDuration]);
//查看资源的方向，图片的旋转方向
NSLog(@"ALAssetPropertyOrientation:%@",[asset valueForProperty:ALAssetPropertyOrientation]);
//查看资源的创建时间
NSLog(@"ALAssetPropertyDate:%@",[asset valueForProperty:ALAssetPropertyDate]);
//查看资源的描述信息
NSLog(@"ALAssetPropertyRepresentations:%@",[asset valueForProperty:ALAssetPropertyRepresentations]);
NSLog(@"ALAssetPropertyURLs:%@",[asset valueForProperty:ALAssetPropertyURLs]);
//查看资源的url路径
NSLog(@"ALAssetPropertyAssetURL:%@",[asset valueForProperty:ALAssetPropertyAssetURL]);
} failureBlock:^(NSError *error) {
}];
//通过url地址获取相册资源中的一个相册
[_library groupForURL:groupURL resultBlock:^(ALAssetsGroup *group) {
NSLog(@"ALAssetsGroupPropertyName:%@",[group valueForProperty:ALAssetsGroupPropertyName]);
} failureBlock:^(NSError *error) {
}];
//根据选择的类型遍历相册资源中的相对应类型的所有相册，其中stop行参是指针，表示是否停止迭代，当赋值为false则停止
/*
enum {
ALAssetsGroupLibrary = (1 << 0),
ALAssetsGroupAlbum = (1 << 1),
ALAssetsGroupEvent = (1 << 2),
ALAssetsGroupFaces = (1 << 3),
ALAssetsGroupSavedPhotos = (1 << 4),
ALAssetsGroupPhotoStream = (1 << 5),
ALAssetsGroupAll = 0xFFFFFFFF,
};
*/
[_library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
NSLog(@"group name:%@",[group valueForProperty:ALAssetsGroupPropertyName]);
} failureBlock:^(NSError *error) {
}];
//保存图片到系统默认的相册中，使用nsdata的形式，并返回照片的url地址
[_library writeImageDataToSavedPhotosAlbum:nil metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {
}];
//保存图片到系统默认的相册中，使用cgimageref的形式，并返回照片的url地址
[_library writeImageToSavedPhotosAlbum:nil metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {
}];
//保存图片到系统默认的相册中，使用cgimageref的形式，并且选择图片以什么旋转方向的形式保存，并返回照片的url地址
/*
typedef enum {
ALAssetOrientationUp, // default orientation
ALAssetOrientationDown, // 180 deg rotation
ALAssetOrientationLeft, // 90 deg CCW
ALAssetOrientationRight, // 90 deg CW
ALAssetOrientationUpMirrored, // as above but image mirrored along other axis. horizontal flip
ALAssetOrientationDownMirrored, // horizontal flip
ALAssetOrientationLeftMirrored, // vertical flip
ALAssetOrientationRightMirrored, // vertical flip
} ALAssetOrientation;
*/
UIImage* image = [UIImage imageNamed:@"test.png"];
[_library writeImageToSavedPhotosAlbum:[image CGImage]
orientation:ALAssetOrientationLeft completionBlock:^(NSURL *assetURL,
NSError *error) {
NSLog(@"save image:%@",assetURL);
}];