persist stopwatches

MultiChrono/Stopwatch.swift

@@ -8,8 +8,8 @@
 import Foundation
 import Combine
 
-class Stopwatch: ObservableObject, Identifiable {
-    let id = UUID()
+class Stopwatch: ObservableObject, Identifiable, Codable {
+    let id: UUID
     @Published var name: String
     @Published var elapsedTime: TimeInterval = 0
     @Published var isRunning: Bool = false
@@ -18,10 +18,44 @@ class Stopwatch: ObservableObject, Identifiable {
     private var startTime: Date?
     private var accumulatedTime: TimeInterval = 0
     
+    enum CodingKeys: String, CodingKey {
+        case id, name, elapsedTime, isRunning, startTime, accumulatedTime
+    }
+    
     init(name: String) {
+        self.id = UUID()
         self.name = name
     }
     
+    required init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(UUID.self, forKey: .id)
+        name = try container.decode(String.self, forKey: .name)
+        elapsedTime = try container.decode(TimeInterval.self, forKey: .elapsedTime)
+        isRunning = try container.decode(Bool.self, forKey: .isRunning)
+        startTime = try container.decodeIfPresent(Date.self, forKey: .startTime)
+        accumulatedTime = try container.decode(TimeInterval.self, forKey: .accumulatedTime)
+        
+        if isRunning {
+            // Restart the timer if it was running.
+            // We also need to update current elapsedTime based on how much time passed since startTime
+            if let start = startTime {
+                 elapsedTime = accumulatedTime + Date().timeIntervalSince(start)
+            }
+            startTimer()
+        }
+    }
+    
+    func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(id, forKey: .id)
+        try container.encode(name, forKey: .name)
+        try container.encode(elapsedTime, forKey: .elapsedTime)
+        try container.encode(isRunning, forKey: .isRunning)
+        try container.encode(startTime, forKey: .startTime)
+        try container.encode(accumulatedTime, forKey: .accumulatedTime)
+    }
+    
     deinit {
         timer?.cancel()
     }
@@ -31,8 +65,11 @@ class Stopwatch: ObservableObject, Identifiable {
         
         startTime = Date()
         isRunning = true
-        
-        timer = Timer.publish(every: 0.1, on: .main, in: .common)
+        startTimer()
+    }
+    
+    private func startTimer() {
+        timer = Timer.publish(every: 0.01, on: .main, in: .common)
             .autoconnect()
             .sink { [weak self] _ in
                 self?.tick()
@@ -71,12 +108,12 @@ class Stopwatch: ObservableObject, Identifiable {
         let hours = Int(elapsedTime) / 3600
         let minutes = Int(elapsedTime) / 60 % 60
         let seconds = Int(elapsedTime) % 60
-        let tenths = Int((elapsedTime.truncatingRemainder(dividingBy: 1)) * 10)
+        let tenths = Int((elapsedTime.truncatingRemainder(dividingBy: 1)) * 100)
         
         if hours > 0 {
-            return String(format: "%02i:%02i:%02i.%01i", hours, minutes, seconds, tenths)
+            return String(format: "%02i:%02i:%02i.%02i", hours, minutes, seconds, tenths)
         } else {
-            return String(format: "%02i:%02i.%01i", minutes, seconds, tenths)
+            return String(format: "%02i:%02i.%02i", minutes, seconds, tenths)
         }
     }
 }