Add example app (#1)

Example App/Example App.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

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+<?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>

Example App/Example App/Assets.xcassets/AccentColor.colorset/Contents.json

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+{
+  "colors" : [
+    {
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Example App/Example App/Assets.xcassets/AppIcon.appiconset/Contents.json

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+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Example App/Example App/Assets.xcassets/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Example App/Example App/Author.swift

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+import Foundation
+import CoreData
+import CoreDataPlus
+
+extension Author: ManagedObjectCountable,
+                ManagedObjectSearchable,
+                ManagedObjectDeletable,
+                ManagedObjectFindOrCreateBy {
+
+}

Example App/Example App/Book.swift

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+import Foundation
+import CoreData
+import CoreDataPlus
+
+extension Book: ManagedObjectCountable,
+                ManagedObjectSearchable,
+                ManagedObjectDeletable,
+                ManagedObjectFindOrCreateBy {
+
+}

Example App/Example App/BookDetailView.swift

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+// 
+
+import Foundation
+import SwiftUI
+import CoreData
+import CoreDataPlus
+
+struct BookDetailView: View {
+    @Environment(\.managedObjectContext) private var viewContext
+    @ObservedObject var book: Book
+
+    public var body: some View {
+        ScrollView {
+            VStack {
+                Text(book.title ?? "No title")
+                    .font(.title)
+
+                ForEach((book.authors?.allObjects as? [Author] ?? []), id: \.self) { author in
+                    HStack(spacing: 5) {
+                        Text(author.name ?? "No name")
+                        Button("❌", action: {
+                            book.removeFromAuthors(author)
+                        })
+                    }
+                }
+
+
+                VStack(spacing: 100) {
+                    Button("Add author\nHaruki Murakami", action: {
+                        let murakami = Author.findOrCreate(column: "name", value: "Haruki Murakami", context: viewContext)
+                        book.addToAuthors(murakami)
+                    })
+                    .buttonStyle(.bordered)
+
+                    Button("Add author\nMurakami, J.K., or Millet", action: {
+                        let names = [
+                            "Haruki Murakami",
+                            "J. K. Rowling",
+                            "Lydia Millet"
+                        ]
+
+                        book.addToAuthors(Author.findOrCreate(column: "name", value: names.randomElement()!, context: viewContext))
+                    })
+                    .buttonStyle(.bordered)
+
+                    Button("Add new fictional author", action: {
+                        book.addToAuthors(Author.findOrCreate(column: "name", value: "Author \(Int.random(in: 1...1000))", context: viewContext))
+                    })
+                    .buttonStyle(.bordered)
+
+                    Button("Add new fictional author", action: {
+                        book.addToAuthors(Author.findOrCreate(column: "name", value: "Author \(Int.random(in: 1...1000))", context: viewContext))
+                    })
+                    .buttonStyle(.bordered)
+                }
+
+
+            }
+        }
+    }
+}

Example App/Example App/ContentView.swift

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+//
+//  ContentView.swift
+//  Example App
+//
+//  Created by Will Jessop on 10/26/22.
+//
+
+import SwiftUI
+import CoreData
+import CoreDataPlus
+
+struct ContentView: View {
+    @Environment(\.managedObjectContext) private var viewContext
+
+    @FetchRequest(
+        sortDescriptors: [NSSortDescriptor(keyPath: \Book.title, ascending: true)],
+        animation: .default)
+    private var books: FetchedResults<Book>
+
+    var body: some View {
+        NavigationView {
+            List {
+                Section(footer: VStack(alignment: .leading) {
+                    Spacer()
+                    HStack {
+                        Image(systemName: "plus")
+                        Text("Add test data").fontWeight(.bold)
+                    }
+                    .foregroundColor(.blue)
+                    .onTapGesture {
+                        self.addTestData()
+                    }
+                    Spacer(minLength: 20)
+
+                    Text("Saving").underline()
+                    Text("Core Data is saved to disk when the app goes into the background.\n\nOr you can click the \"Save all\" button.")
+                    Spacer(minLength: 20)
+
+                    Text("New Book object with id = 100").underline()
+                    Text("Demonstrates what happens when you create a variable using findOrCreate(id:)")
+                    Spacer(minLength: 20)
+
+                })  {
+                    ForEach(books) { book in
+                        NavigationLink {
+                            BookDetailView(book: book)
+                        } label: {
+                            Text(book.title!)
+                            Text("\((book.authors?.allObjects as! [Author]).map { author in author.name! }.joined())")
+                                .font(.caption)
+                        }
+                    }
+                    .onDelete(perform: deleteItems)
+                }
+
+
+
+            }
+            .toolbar {
+                ToolbarItemGroup(placement: .navigationBarTrailing) {
+
+
+                    Button(action: addBook) {
+                        Label("Add Book", systemImage: "plus")
+                    }
+
+                    Button(action: deleteAllBooksAndAuthors) {
+                        Label("Delete all books and authors", systemImage: "trash")
+                    }
+
+                }
+
+                ToolbarItemGroup(placement: .navigationBarLeading) {
+                    Button("New Book object with id = 100", action: {
+                        let book = Book.findOrCreate(id: "100", context: viewContext)
+                        book.title = "Book(id=100) last touched \(Date().formatted(date: .abbreviated, time: .complete))"
+                    })
+                }
+
+                ToolbarItemGroup(placement: .bottomBar) {
+
+                    Button("Save all", action: {
+                        try! viewContext.save()
+                    })
+                    .buttonStyle(.borderedProminent)
+
+                    Spacer()
+                    Button("Delete authors", action: {
+                        Author.destroyAll(context: viewContext)
+                    })
+                    .foregroundColor(.red)
+
+                    Button("Delete books", action: {
+                        Book.destroyAll(context: viewContext)
+                    })
+                    .foregroundColor(.red)
+
+
+
+
+                }
+
+            }
+            Text("Select an item")
+        }
+        .navigationViewStyle(.stack)
+    }
+
+    private func addTestData() {
+        // create some authors
+        // using the name field as the unique identifier
+        // TODO: add better docs on how to handle id/identifiable with core data (not library-specific)
+        let murakami = Author.findOrCreate(column: "name", value: "Haruki Murakami", context: viewContext)
+        let jk = Author.findOrCreate(column: "name", value: "J. K. Rowling", context: viewContext)
+
+        // using id as the unique identifier
+        let lydia = Author.findOrCreate(id: "1234", context: viewContext)
+        lydia.name = "Lydia Millet"
+
+        var authors = [murakami, jk, lydia]
+
+        for _ in 0..<10 {
+            let newItem = Book.findOrCreate(id: UUID().uuidString, context: viewContext)
+            newItem.title = "Harry Potter Vol. \(Int.random(in: 1...1000))"
+
+            newItem.addToAuthors(authors.randomElement()!)
+
+            // add a 2nd author to some books
+            if Int.random(in: 1...100) > 50 {
+                newItem.addToAuthors(authors.randomElement()!)
+            }
+        }
+    }
+    private func deleteAllBooks() {
+        Book.destroyAll(context: viewContext)
+    }
+    private func deleteAllAuthors() {
+        Author.destroyAll(context: viewContext)
+    }
+    private func deleteAllBooksAndAuthors() {
+        Author.destroyAll(context: viewContext)
+        Book.destroyAll(context: viewContext)
+    }
+
+    private func addBook() {
+        let newBook = Book.findOrCreate(id: UUID().uuidString, context: viewContext)
+        newBook.title = "Book \(Int.random(in: 1...1000))"
+    }
+
+    private func deleteItems(offsets: IndexSet) {
+        withAnimation {
+            offsets.map { books[$0] }.forEach(viewContext.delete)
+        }
+    }
+}
+

Example App/Example App/Example_App.xcdatamodeld/.xccurrentversion

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+<?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>_XCCurrentVersionName</key>
+	<string>Example_App.xcdatamodel</string>
+</dict>
+</plist>

Example App/Example App/Example_App.xcdatamodeld/Example_App.xcdatamodel/contents

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="21279" systemVersion="21G72" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
+    <entity name="Author" representedClassName="Author" syncable="YES" codeGenerationType="class">
+        <attribute name="id" optional="YES" attributeType="String"/>
+        <attribute name="name" attributeType="String" defaultValueString=""/>
+        <relationship name="books" optional="YES" toMany="YES" deletionRule="Nullify" destinationEntity="Book" inverseName="authors" inverseEntity="Book"/>
+    </entity>
+    <entity name="Book" representedClassName="Book" syncable="YES" codeGenerationType="class">
+        <attribute name="id" attributeType="String"/>
+        <attribute name="title" attributeType="String" defaultValueString=""/>
+        <relationship name="authors" optional="YES" toMany="YES" deletionRule="Nullify" destinationEntity="Author" inverseName="books" inverseEntity="Author"/>
+    </entity>
+</model>

Example App/Example App/Example_AppApp.swift

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+//
+//  Example_AppApp.swift
+//  Example App
+//
+//  Created by Will Jessop on 10/26/22.
+//
+
+import SwiftUI
+
+@main
+struct Example_AppApp: App {
+    let persistenceController = PersistenceController.shared
+    @Environment(\.scenePhase) private var phase
+
+    var body: some Scene {
+        WindowGroup {
+            ContentView()
+                .environment(\.managedObjectContext, persistenceController.container.viewContext)
+        }
+        .onChange(of: phase) { newPhase in
+            switch newPhase {
+            case .background:
+                try! persistenceController.container.viewContext.save()
+            default:
+                break
+            }
+        }
+    }
+
+}

Example App/Example App/Persistence.swift

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+//
+//  Persistence.swift
+//  Example App
+//
+//  Created by Will Jessop on 10/26/22.
+//
+
+import CoreData
+import CoreDataPlus
+
+struct PersistenceController {
+    static let shared = PersistenceController()
+
+    static var preview: PersistenceController = {
+        let result = PersistenceController(inMemory: true)
+        let viewContext = result.container.viewContext
+
+
+
+        try! viewContext.save()
+
+        return result
+    }()
+
+    let container: NSPersistentContainer
+
+    init(inMemory: Bool = false) {
+        container = NSPersistentContainer(name: "Example_App")
+        if inMemory {
+            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
+        }
+        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
+            if let error = error as NSError? {
+                // Replace this implementation with code to handle the error appropriately.
+                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
+
+                /*
+                 Typical reasons for an error here include:
+                 * The parent directory does not exist, cannot be created, or disallows writing.
+                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
+                 * The device is out of space.
+                 * The store could not be migrated to the current model version.
+                 Check the error message to determine what the actual problem was.
+                 */
+                fatalError("Unresolved error \(error), \(error.userInfo)")
+            }
+        })
+        container.viewContext.automaticallyMergesChangesFromParent = true
+    }
+}