Add files

Source/DataFilter/DataFilter.swift

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+import Foundation
+import CoreData
+
+/**
+ Helps you filter insertions, deletions and updates by comparing your JSON dictionary with your Core Data local objects.
+ It also provides uniquing for you locally stored objects and automatic removal of not found ones.
+ */
+class DataFilter: NSObject {
+    struct Operation: OptionSet {
+        let rawValue: Int
+
+        init(rawValue: Int) {
+            self.rawValue = rawValue
+        }
+
+        static let insert = Operation(rawValue: 1 << 0)
+        static let update = Operation(rawValue: 1 << 1)
+        static let delete = Operation(rawValue: 1 << 2)
+        static let all: Operation = [.insert, .update, .delete]
+    }
+
+    class func changes(_ changes: [[String: Any]],
+                       inEntityNamed entityName: String,
+                       localPrimaryKey: String,
+                       remotePrimaryKey: String,
+                       context: NSManagedObjectContext,
+                       inserted: (_ json: [String: Any]) -> Void,
+                       updated: (_ json: [String: Any], _ updatedObject: NSManagedObject) -> Void) {
+        self.changes(changes, inEntityNamed: entityName, predicate: nil, operations: .all, localPrimaryKey: localPrimaryKey, remotePrimaryKey: remotePrimaryKey, context: context, inserted: inserted, updated: updated)
+    }
+
+    class func changes(_ changes: [[String: Any]],
+                       inEntityNamed entityName: String,
+                       predicate: NSPredicate?,
+                       operations: Operation,
+                       localPrimaryKey: String,
+                       remotePrimaryKey: String,
+                       context: NSManagedObjectContext,
+                       inserted: (_ json: [String: Any]) -> Void,
+                       updated: (_ json: [String: Any], _ updatedObject: NSManagedObject) -> Void) {
+        // `DataObjectIDs.objectIDsInEntityNamed` also deletes all objects that don't have a primary key or that have the same primary key already found in the context
+        let primaryKeysAndObjectIDs = context.managedObjectIDs(in: entityName, usingAsKey: localPrimaryKey, predicate: predicate) as [NSObject: NSManagedObjectID]
+        let localPrimaryKeys = Array(primaryKeysAndObjectIDs.keys)
+        let remotePrimaryKeys = changes.map { $0[remotePrimaryKey] }
+        let remotePrimaryKeysWithoutNils = (remotePrimaryKeys.filter { (($0 as? NSObject) != NSNull()) && ($0 != nil) } as! [NSObject?]) as! [NSObject]
+
+        var remotePrimaryKeysAndChanges = [NSObject: [String: Any]]()
+        for (primaryKey, change) in zip(remotePrimaryKeysWithoutNils, changes) {
+            remotePrimaryKeysAndChanges[primaryKey] = change
+        }
+
+        var intersection = Set(remotePrimaryKeysWithoutNils)
+        intersection.formIntersection(Set(localPrimaryKeys))
+        let updatedObjectIDs = Array(intersection)
+
+        var deletedObjectIDs = localPrimaryKeys
+        deletedObjectIDs = deletedObjectIDs.filter { value in
+            !remotePrimaryKeysWithoutNils.contains { $0.isEqual(value) }
+        }
+
+        var insertedObjectIDs = remotePrimaryKeysWithoutNils
+        insertedObjectIDs = insertedObjectIDs.filter { value in
+            !localPrimaryKeys.contains { $0.isEqual(value) }
+        }
+
+        if operations.contains(.delete) {
+            for fetchedID in deletedObjectIDs {
+                let objectID = primaryKeysAndObjectIDs[fetchedID]!
+                let object = context.object(with: objectID)
+                context.delete(object)
+            }
+        }
+
+        if operations.contains(.insert) {
+            for fetchedID in insertedObjectIDs {
+                let objectDictionary = remotePrimaryKeysAndChanges[fetchedID]!
+                inserted(objectDictionary)
+            }
+        }
+
+        if operations.contains(.update) {
+            for fetchedID in updatedObjectIDs {
+                let JSON = remotePrimaryKeysAndChanges[fetchedID]!
+                let objectID = primaryKeysAndObjectIDs[fetchedID]!
+                let object = context.object(with: objectID)
+                updated(JSON, object)
+            }
+        }
+    }
+}