Split IntervalTimer model into view and coredata models

Trying to use the same object for the view and Core Data was a bit
clumsy and made working with SwiftUI previews difficult. Splitting
them up fixed the issue at the expense of a little more maintenance
work.

IntervalTimer/ActiveTimerView.swift

@@ -127,7 +127,25 @@ struct LabeledCounter: View {
 }
 
 struct ActiveTimerView_Previews: PreviewProvider {
+    static var dataStore: TimerDataStore {
+        get {
+            let store = TimerDataStore() {}
+            store.openTimer(IntervalTimer(
+                id: UUID(),
+                name: "Test",
+                description: nil,
+                warmUpDuration: 300,
+                lowIntensityDuration: 10,
+                highIntensityDuration: 20,
+                restDuration: 50,
+                cooldownDuration: 300,
+                sets: 4,
+                rounds: 2
+            ))
+            return store
+        }
+    }
     static var previews: some View {
-        ActiveTimerView().environmentObject(TimerDataStore() {})
+        ActiveTimerView().environmentObject(dataStore)
     }
 }

IntervalTimer/IntervalTimer.swift

@@ -11,7 +11,20 @@ import CoreData
 import Foundation
 import SwiftUI
 
-class IntervalTimer: NSManagedObject, Identifiable {
+struct IntervalTimer: Identifiable, Equatable {
+    let id: UUID?
+    let name: String
+    let description: String?
+    let warmUpDuration: Int64
+    let lowIntensityDuration: Int64
+    let highIntensityDuration: Int64
+    let restDuration: Int64
+    let cooldownDuration: Int64
+    let sets: Int64
+    let rounds: Int64
+}
+
+class IntervalTimerMO: NSManagedObject, Identifiable {
     @NSManaged var id: UUID?
     @NSManaged var name: String
     @NSManaged var userDescription: String?
@@ -72,6 +85,34 @@ extension IntervalTimer {
             return warmUpDuration + ((((lowIntensityDuration + highIntensityDuration) * sets) + restDuration) * rounds) + cooldownDuration
         }
     }
+    
+    func copy(toMO: IntervalTimerMO) {
+        toMO.id = self.id
+        toMO.name = self.name
+        toMO.userDescription = self.description
+        toMO.warmUpDuration = self.warmUpDuration
+        toMO.lowIntensityDuration = self.lowIntensityDuration
+        toMO.highIntensityDuration = self.highIntensityDuration
+        toMO.restDuration = self.restDuration
+        toMO.cooldownDuration = self.cooldownDuration
+        toMO.sets = self.sets
+        toMO.rounds = self.rounds
+    }
+    
+    static func create(fromMO: IntervalTimerMO) -> IntervalTimer {
+        return IntervalTimer(
+            id: fromMO.id,
+            name: fromMO.name,
+            description: fromMO.userDescription,
+            warmUpDuration: fromMO.warmUpDuration,
+            lowIntensityDuration: fromMO.lowIntensityDuration,
+            highIntensityDuration: fromMO.highIntensityDuration,
+            restDuration: fromMO.restDuration,
+            cooldownDuration: fromMO.cooldownDuration,
+            sets: fromMO.sets,
+            rounds: fromMO.rounds
+        )
+    }
 }
 
 struct ActiveTimerState {

IntervalTimer/IntervalTimer.xcdatamodeld/IntervalTimer.xcdatamodel/contents

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="17192" systemVersion="19H2" minimumToolsVersion="Automatic" sourceLanguage="Swift" usedWithCloudKit="YES" userDefinedModelVersionIdentifier="">
-    <entity name="IntervalTimer" representedClassName=".IntervalTimer" syncable="YES">
+    <entity name="IntervalTimer" representedClassName=".IntervalTimerMO" syncable="YES">
         <attribute name="cooldownDuration" optional="YES" attributeType="Integer 64" defaultValueString="0" usesScalarValueType="YES"/>
         <attribute name="highIntensityDuration" optional="YES" attributeType="Integer 64" defaultValueString="0" usesScalarValueType="YES"/>
         <attribute name="id" optional="YES" attributeType="UUID" usesScalarValueType="NO"/>

IntervalTimer/TimerDataStore.swift

@@ -183,20 +183,14 @@ class TimerDataStore: ObservableObject {
     }
     
     func loadTimers() {
-        DispatchQueue.global(qos: .background).async {
         let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "IntervalTimer")
         do {
-                let fetchedTimers = try self.persistentContainer.viewContext.fetch(fetchRequest) as! [IntervalTimer]
+            let fetchedTimers = try self.persistentContainer.viewContext.fetch(fetchRequest) as! [IntervalTimerMO]
-                DispatchQueue.main.async {
+            self.timers = .success(fetchedTimers.map { IntervalTimer.create(fromMO: $0) })
-                    self.timers = .success(fetchedTimers)
-                }
         } catch {
-                DispatchQueue.main.async {
             self.timers = .failure(.failed(error))
         }
     }
-        }
-    }
     
     func saveTimer(
         id: UUID? = nil,
@@ -210,18 +204,11 @@ class TimerDataStore: ObservableObject {
         sets: Int64,
         rounds: Int64
     ) {
-        var timer: IntervalTimer
+        var timer: IntervalTimerMO
         if let uuid = id {
-            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "IntervalTimer")
+            timer = loadTimer(byId: uuid)!
-            fetchRequest.predicate = NSPredicate(format: "id = %@", uuid.uuidString)
-            let result = try! persistentContainer.viewContext.fetch(fetchRequest) as! [IntervalTimer]
-            if result.count == 1 {
-                timer = result[0]
         } else {
-                timer = IntervalTimer.init(entity: NSEntityDescription.entity(forEntityName: "IntervalTimer", in: persistentContainer.viewContext)!, insertInto: persistentContainer.viewContext) as IntervalTimer
+            timer = IntervalTimerMO.init(entity: NSEntityDescription.entity(forEntityName: "IntervalTimer", in: persistentContainer.viewContext)!, insertInto: persistentContainer.viewContext) as IntervalTimerMO
-            }
-        } else {
-            timer = IntervalTimer.init(entity: NSEntityDescription.entity(forEntityName: "IntervalTimer", in: persistentContainer.viewContext)!, insertInto: persistentContainer.viewContext) as IntervalTimer
         }
         
         timer.id = id ?? UUID()
@@ -242,19 +229,31 @@ class TimerDataStore: ObservableObject {
         loadTimers()
         if let currentState = activeTimer {
             if currentState.timer.id == timer.id {
-                activeTimer = currentState.copy(timer: timer)
+                activeTimer = currentState.copy(timer: IntervalTimer.create(fromMO: timer))
             }
         }
     }
 
     func deleteTimer(at: IndexSet) {
-        let timer = try!  self.timers.get()[at.first!]
+        guard let timer = loadTimer(byId: try! self.timers.get()[at.first!].id!) else {
+            return
+        }
         let viewContext = persistentContainer.viewContext
         viewContext.delete(timer)
         try! viewContext.save()
         loadTimers()
     }
     
+    private func loadTimer(byId: UUID) -> IntervalTimerMO? {
+        let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "IntervalTimer")
+        fetchRequest.predicate = NSPredicate(format: "id = %@", byId.uuidString)
+        let result = try! persistentContainer.viewContext.fetch(fetchRequest) as! [IntervalTimerMO]
+        if result.count == 1 {
+            return result[0]
+        }
+        return nil
+    }
+    
     private func loadSound(_ phase: Phase) {
         let filePath = Bundle.main.path(forResource: phase.rawValue, ofType: "mp3")
         let url = NSURL(fileURLWithPath: filePath!)

IntervalTimer/TimerFormView.swift

@@ -162,7 +162,7 @@ struct TimerFormView: View {
             self.title = "New Timer"
         }
         self._name = State(initialValue: timer?.name ?? "")
-        self._description = State(initialValue: timer?.userDescription ?? "")
+        self._description = State(initialValue: timer?.description ?? "")
         self._warmDuration = State(initialValue: timer?.warmUpDuration ?? 300)
         self._lowDuration = State(initialValue: timer?.lowIntensityDuration ?? 30)
         self._highDuration = State(initialValue: timer?.highIntensityDuration ?? 60)

IntervalTimer/TimerListView.swift

@@ -29,8 +29,8 @@ struct TimerListView: View {
                                 VStack(alignment: .leading) {
                                     Text(timer.name)
                                         .lineLimit(1)
-                                    if timer.userDescription?.count ?? 0 > 0 {
+                                    if timer.description?.count ?? 0 > 0 {
-                                        Text(timer.userDescription!)
+                                        Text(timer.description!)
                                             .font(.subheadline)
                                             .foregroundColor(.secondary)
                                             .lineLimit(1)

IntervalTimerTests/IntervalTimerTests.swift

@@ -30,5 +30,4 @@ class IntervalTimerTests: XCTestCase {
             // Put the code you want to measure the time of here.
         }
     }
-
 }