Marcus S. Zarra đã truyền cảm hứng cho tôi để đưa ý tưởng đệ quy vào một phiên bản hoạt động. Trong phiên bản này, bạn không cần đặt khóa trong CoreData và bạn có thể cắt và dán nó vào dự án của mình :-)
// MARK: - encoding and decoding CoreData entity to dictionary
func dataStructureFromManagedObject( managedObject:NSManagedObject?, parentEntity: NSEntityDescription? = nil) -> NSMutableDictionary {
if (managedObject != nil) {
var attributesByName: NSDictionary = managedObject!.entity.attributesByName
var relationshipsByName: NSDictionary = managedObject!.entity.relationshipsByName
var valuesImmutableDictionary: NSDictionary = managedObject!.dictionaryWithValuesForKeys( attributesByName.allKeys)
var valuesDictionary: NSMutableDictionary = valuesImmutableDictionary.mutableCopy() as NSMutableDictionary
valuesDictionary.setObject( managedObject!.entity.name!, forKey: "ManagedObjectName")
for relationshipNameObject in relationshipsByName.allKeys {
var relationshipName: NSString = relationshipNameObject as NSString
var relationshipDescription: NSRelationshipDescription? = relationshipsByName.objectForKey( relationshipName) as? NSRelationshipDescription
if !relationshipDescription!.toMany {
// ono to one
if parentEntity == nil || (relationshipDescription! as NSRelationshipDescription).destinationEntity != parentEntity! {
// no parent or relationship is "downward" -> object for relationship must be added
var relationshipObject: NSManagedObject? = managedObject!.valueForKey( relationshipName) as? NSManagedObject
var relationshipObjectDictionary: NSMutableDictionary = self.dataStructureFromManagedObject( relationshipObject, parentEntity: managedObject?.entity)
valuesDictionary.setObject( relationshipObjectDictionary, forKey: relationshipName)
} else {
// relationship is "upward" -> nothing to do
}
} else {
// one to many -> all objects must be added
var relationshipObjects: NSSet = managedObject!.mutableSetValueForKey( relationshipName)
var relationshipArray:NSMutableArray = []
for relationshipObjectRaw in relationshipObjects {
var relationshipObject:NSManagedObject? = relationshipObjectRaw as? NSManagedObject
if relationshipObject != nil && !relationshipObject!.entity.isKindOfEntity( managedObject!.entity) {
relationshipArray.addObject(self.dataStructureFromManagedObject( relationshipObject, parentEntity: managedObject?.entity))
}
}
valuesDictionary.setObject( relationshipArray, forKey: relationshipName)
}
}
return valuesDictionary
} else {
return NSMutableDictionary()
}
}
func managedObjectFromStructure( structureDictionary: NSDictionary, moc: NSManagedObjectContext, parentObject: NSManagedObject? = nil) -> NSManagedObject {
if structureDictionary.count > 0 {
var objectName:NSString = structureDictionary.objectForKey( "ManagedObjectName") as NSString
var managedObject:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName( objectName, inManagedObjectContext: moc) as NSManagedObject
var relationshipsByName: NSDictionary = managedObject.entity.relationshipsByName
var realObjectStructure:NSMutableDictionary = structureDictionary.mutableCopy() as NSMutableDictionary
realObjectStructure.removeObjectForKey( "ManagedObjectName")
for key in realObjectStructure.allKeys {
// search for "ManagedObjectName" relationship entrys and delete them before filling the managedObject from this structure
for relationshipName in relationshipsByName.allKeys {
if relationshipName as NSString == key as NSString {
realObjectStructure.removeObjectForKey( key)
}
}
}
managedObject.setValuesForKeysWithDictionary( realObjectStructure)
// the main object with attributes is created. Now care about the relationships
for relationshipName in managedObject.entity.relationshipsByName.keys {
var description:NSRelationshipDescription = relationshipsByName.objectForKey( relationshipName) as NSRelationshipDescription
if !description.toMany {
// to one relationship
if parentObject == nil || description.destinationEntity != parentObject!.entity {
// no parent or relationship is "downward" -> recurse structure to add
var childStructureDictionary:NSDictionary = structureDictionary.objectForKey( relationshipName) as NSDictionary
if childStructureDictionary.count > 0 {
// dictionary not empty -> object must be created and added
var childObject:NSManagedObject? = self.managedObjectFromStructure( childStructureDictionary, moc: moc, parentObject: managedObject)
// validateForUpdate
var error:NSError?
if !managedObject.validateForUpdate( &error) {
println("Error: Object not in valid state for update!!! -> \(error)")
} else {
managedObject.setValue( childObject, forKey: relationshipName as NSString)
}
} else {
// relationship is "upward" -> nothing to do
}
}
} else {
// to many relationship
var relationshipSet:NSMutableSet = managedObject.mutableSetValueForKey( relationshipName as NSString)
var relationshipArray:NSArray = structureDictionary.objectForKey( relationshipName as NSString) as NSArray
for childStructureDictionary in relationshipArray {
if childStructureDictionary.count > 0 {
// dictionary not empty -> object must be created and added
var childObject:NSManagedObject = self.managedObjectFromStructure( childStructureDictionary as NSDictionary, moc: moc, parentObject: managedObject)
// validateForUpdate
var error:NSError?
if !managedObject.validateForUpdate( &error) {
println( "Error: Object not in valid state for update!!! -> \(error)")
} else {
relationshipSet.addObject( childObject)
}
} else {
// no object was behind the relationship -> nothing to do
}
}
// save set
managedObject.setValue( relationshipSet, forKey: relationshipName as NSString)
}
}
// final check validateForUpdate
var error:NSError?
if !managedObject.validateForUpdate( &error) {
println( "Error: Object not in valid state for update although all previous check are passed!!! -> \(error)")
}
return managedObject
} else {
println( "Error: structure for object was empty. this should not happen at this point")
var objectName:NSString = structureDictionary.objectForKey( "ManagedObjectName") as NSString
var managedObject:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName( objectName, inManagedObjectContext: moc) as NSManagedObject
return managedObject
}
}
func dataStructuresFromManagedObjects( managedObjects: NSArray) -> NSArray {
var dataArray:NSMutableArray = []
for managedObject in managedObjects {
dataArray.addObject( self.dataStructureFromManagedObject(managedObject as? NSManagedObject))
}
return dataArray
}
Chìa khóa ở đây là chuyển thực thể mẹ làm đối số cho đệ quy, vì vậy chúng ta có thể quyết định mối quan hệ nào chúng ta phải điền vào dữ liệu. Vì vậy, cả hai chức năng: dataStructureFromManagedObjectvà managedObjectFromStructurecó thể mã hóa và giải mã bất kỳ đối tượng thực thể nào từ CoreData thành một từ điển và trở lại thành một đối tượng.
NSJSONSerializationdeveloper.apple.com/library/mac/#documentation/Foundation/… stackoverflow.com/questions/6726899/nsjsonserialization-in-ios5