Move fetchObjectsWithIDs from AttachmentsTable to default protocol implementation since AuthorsTable needs the exact same thing.

Frameworks/RSDatabase/RSDatabase/DatabaseObjectCache.swift

@@ -0,0 +1,33 @@
+//
+//  DatabaseObjectCache.swift
+//  RSDatabase
+//
+//  Created by Brent Simmons on 9/12/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+import Foundation
+
+public final class DatabaseObjectCache {
+
+	private var d = [String: DatabaseObject]()
+
+	public init() {
+		//
+	}
+	public func add(_ databaseObjects: [DatabaseObject]) {
+
+		for databaseObject in databaseObjects {
+			self[databaseObject.databaseID] = databaseObject
+		}
+	}
+
+	public subscript(_ databaseID: String) -> DatabaseObject? {
+		get {
+			return d[databaseID]
+		}
+		set {
+			d[databaseID] = newValue
+		}
+	}
+}