这可能听起来有点重复,但是在搜索一段时间后,我仍然没有得到Swift 3的预期答案。
在创建资产占位符后,当我尝试使用addAssets()
方法添加资产时,Xcode建议我将assetPlacehoder强制转换为FastEnumeration类型。当我这样做时,它会导致异常。有人能帮我解决吗?
这可能听起来有点重复,但是在搜索一段时间后,我仍然没有得到Swift 3的预期答案。
在创建资产占位符后,当我尝试使用addAssets()
方法添加资产时,Xcode建议我将assetPlacehoder强制转换为FastEnumeration类型。当我这样做时,它会导致异常。有人能帮我解决吗?
在需要向相册添加图片之前,使用这个类并请求权限。
class CustomPhotoAlbum: NSObject {
static let albumName = "YourAlbumName"
static let sharedInstance = CustomPhotoAlbum()
var assetCollection: PHAssetCollection!
override init() {
super.init()
if let assetCollection = fetchAssetCollectionForAlbum() {
self.assetCollection = assetCollection
return
}
}
func requestAuthorizationHandler(status: PHAuthorizationStatus) {
if PHPhotoLibrary.authorizationStatus() == PHAuthorizationStatus.authorized {
// ideally this ensures the creation of the photo album even if authorization wasn't prompted till after init was done
print("trying again to create the album")
self.createAlbum()
} else {
print("should really prompt the user to let them know it's failed")
}
}
func createAlbum() {
PHPhotoLibrary.shared().performChanges({
PHAssetCollectionChangeRequest.creationRequestForAssetCollection(withTitle: CustomPhotoAlbum.albumName) // create an asset collection with the album name
}) { success, error in
if success {
self.assetCollection = self.fetchAssetCollectionForAlbum()
} else {
print("error \(String(describing: error))")
}
}
}
func fetchAssetCollectionForAlbum() -> PHAssetCollection? {
let fetchOptions = PHFetchOptions()
fetchOptions.predicate = NSPredicate(format: "title = %@", CustomPhotoAlbum.albumName)
let collection = PHAssetCollection.fetchAssetCollections(with: .album, subtype: .any, options: fetchOptions)
if let _: AnyObject = collection.firstObject {
return collection.firstObject
}
return nil
}
func save(image: UIImage , completion : @escaping () -> ()) {
if assetCollection == nil {
return // if there was an error upstream, skip the save
}
PHPhotoLibrary.shared().performChanges({
let assetChangeRequest = PHAssetChangeRequest.creationRequestForAsset(from: image)
let assetPlaceHolder = assetChangeRequest.placeholderForCreatedAsset
let albumChangeRequest = PHAssetCollectionChangeRequest(for: self.assetCollection)
let enumeration: NSArray = [assetPlaceHolder!]
if self.assetCollection.estimatedAssetCount == 0
{
albumChangeRequest!.addAssets(enumeration)
}
else {
albumChangeRequest!.insertAssets(enumeration, at: [0])
}
}, completionHandler: { status , errror in
completion( )
})
}
}
在需要保存图像的地方调用此方法。
CustomPhotoAlbum.sharedInstance.save(image: YourImage, completion: {
DispatchQueue.main.async(execute: {
//"Any UI update should be in main thread."
})
})