Refactored project to simplify migration and support swift 4.2

Author: wibosco

.travis.yml

@@ -3,10 +3,10 @@ language: objective-c
 cache:
   - bundler
 
-osx_image: xcode9
+osx_image: xcode10.1
 
 before_install:
    - bundle install
 
 script:
-   - bundle exec fastlane run_tests  --verbose
+   - bundle exec fastlane run_unit_tests --verbose

CoreDataMigration-Example.xcodeproj/project.pbxproj

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

CoreDataMigration-Example.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0830"
+   LastUpgradeVersion = "1010"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -26,7 +26,6 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      language = ""
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
          <TestableReference
@@ -56,7 +55,6 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      language = ""
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"

CoreDataMigration-Example.xcodeproj/xcshareddata/xcschemes/CoreDataMigration-Example.xcscheme

@@ -9,13 +9,14 @@
 import UIKit
 import CoreData
 
+@UIApplicationMain
 class AppDelegate: UIResponder, UIApplicationDelegate {
 
     var window: UIWindow?
 
     // MARK: - AppLifecycle
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
 
         CoreDataManager.shared.setup {
             DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { // just for example purposes

CoreDataMigration-Example/Application/AppDelegate.swift

@@ -12,11 +12,13 @@ import CoreData
 class CoreDataManager {
 
     let migrator: CoreDataMigrator
+    private let storeType: String
 
     lazy var persistentContainer: NSPersistentContainer! = {
         let persistentContainer = NSPersistentContainer(name: "CoreDataMigration_Example")
         let description = persistentContainer.persistentStoreDescriptions.first
         description?.shouldInferMappingModelAutomatically = false //inferred mapping will be handled else where
+        description?.type = storeType
 
         return persistentContainer
     }()
@@ -41,7 +43,8 @@ class CoreDataManager {
 
     // MARK: - Init
 
-    init(migrator: CoreDataMigrator = CoreDataMigrator()) {
+    init(storeType: String = NSSQLiteStoreType, migrator: CoreDataMigrator = CoreDataMigrator()) {
+        self.storeType = storeType
         self.migrator = migrator
     }
 

CoreDataMigration-Example/Application/main.swift

@@ -10,7 +10,40 @@ import CoreData
 
 struct CoreDataMigrationStep {
 
-    let source: NSManagedObjectModel
-    let destination: NSManagedObjectModel
-    let mapping: NSMappingModel
+    let sourceModel: NSManagedObjectModel
+    let destinationModel: NSManagedObjectModel
+    let mappingModel: NSMappingModel
+    
+    // MARK: Init
+    
+    init(sourceVersion: CoreDataMigrationVersion, destinationVersion: CoreDataMigrationVersion) {
+        let sourceModel = NSManagedObjectModel.managedObjectModel(forResource: sourceVersion.rawValue)
+        let destinationModel = NSManagedObjectModel.managedObjectModel(forResource: destinationVersion.rawValue)
+        
+        guard let mappingModel = CoreDataMigrationStep.mappingModel(fromSourceModel: sourceModel, toDestinationModel: destinationModel) else {
+            fatalError("Expected modal mapping not present")
+        }
+        
+        self.sourceModel = sourceModel
+        self.destinationModel = destinationModel
+        self.mappingModel = mappingModel
+    }
+    
+    // MARK: - Mapping
+    
+    private static func mappingModel(fromSourceModel sourceModel: NSManagedObjectModel, toDestinationModel destinationModel: NSManagedObjectModel) -> NSMappingModel? {
+        guard let customMapping = customMappingModel(fromSourceModel: sourceModel, toDestinationModel: destinationModel) else {
+            return inferredMappingModel(fromSourceModel:sourceModel, toDestinationModel: destinationModel)
+        }
+        
+        return customMapping
+    }
+    
+    private static func inferredMappingModel(fromSourceModel sourceModel: NSManagedObjectModel, toDestinationModel destinationModel: NSManagedObjectModel) -> NSMappingModel? {
+        return try? NSMappingModel.inferredMappingModel(forSourceModel: sourceModel, destinationModel: destinationModel)
+    }
+    
+    private static func customMappingModel(fromSourceModel sourceModel: NSManagedObjectModel, toDestinationModel destinationModel: NSManagedObjectModel) -> NSMappingModel? {
+        return NSMappingModel(from: [Bundle.main], forSourceModel: sourceModel, destinationModel: destinationModel)
+    }
 }