end of lecture

StopWatch/Base.lproj/Main.storyboard

@@ -50,6 +50,9 @@
                                 <state key="normal" title="Lap">
                                     <color key="titleColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                 </state>
+                                <connections>
+                                    <action selector="lapButtonPressed" destination="BYZ-38-t0r" eventType="touchUpInside" id="xjX-oc-v0f"/>
+                                </connections>
                             </button>
                             <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="0.00" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="XnN-ry-xnq">
                                 <rect key="frame" x="16" y="84" width="382" height="51"/>
@@ -89,6 +92,7 @@
                     </view>
                     <connections>
                         <outlet property="startButton" destination="oec-PD-a3v" id="Uhx-Cw-W0U"/>
+                        <outlet property="timeDisplayLabel" destination="XnN-ry-xnq" id="eIn-nt-Wvp"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>

StopWatch/TimerModel.swift

@@ -10,12 +10,16 @@ import Foundation
 
 protocol UpdateTime {
     func timeUpdated(_ interval: TimeInterval)
+    func lapsUpdated(_ laps: [TimeInterval])
 }
 
 class TimerModel {
     var updateDelegate: UpdateTime?
     var startTime: Date?
     var timer: Timer?
+    var lapTime: Date?
+
+    var laps: [TimeInterval] = []
 
     init() {
     }
@@ -29,6 +33,22 @@ class TimerModel {
         return Date().timeIntervalSince(startTime)
     }
 
+    func lap() -> Void {
+        guard let startTime = self.startTime else {
+            return
+        }
+
+        let now = Date()
+        let baseTime = self.lapTime ?? startTime
+        let interval = now.timeIntervalSince(baseTime)
+        self.laps.append(interval)
+
+        // we'll talk about this in detail later
+        DispatchQueue.main.async {
+            self.updateDelegate?.lapsUpdated(self.laps)
+        }
+    }
+
     func startTimer() -> Void {
         self.startTime = Date()
         // don't worry about runloop details, we'll talk about it later

StopWatch/ViewController.swift

@@ -8,9 +8,49 @@
 
 import UIKit
 
-class ViewController: UIViewController, UpdateTime {
+class ViewController: UIViewController, UpdateTime, UITableViewDataSource, UITableViewDelegate {
+
+    func lapsUpdated(_ laps: [TimeInterval]) {
+        var displayLaps: [LapDisplay] = []
+        for (index, lap) in laps.reversed().enumerated() {
+            displayLaps.append(LapDisplay(lapNumber: laps.count - index, lapTime: lap))
+        }
+        self.laps = displayLaps
+    }
+
+
+    struct LapDisplay {
+        let lapNumber: Int
+        let lapTime: TimeInterval
+    }
+
+    @IBOutlet weak var timeDisplayLabel: UILabel!
+    var laps: [LapDisplay]?
+
+    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        // by default there is one section for each tableview
+        return self.laps?.count ?? 0
+    }
+
+    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+        guard let laps = self.laps else {
+            return UITableViewCell()
+        }
+
+        let lap = laps[indexPath.row]
+
+        // the identifier is like the type of the cell
+        let cell = tableView.dequeueReusableCell(withIdentifier: "lapCell") ?? UITableViewCell(style: .subtitle, reuseIdentifier: "lapCell")
+
+        // IMPORTANT: make sure to set all fields!
+        cell.textLabel?.text = "Lap \(lap.lapNumber)"
+        cell.detailTextLabel?.text = String(format: "%0.02f", lap.lapTime)
+
+        return cell
+    }
+
     func timeUpdated(_ interval: TimeInterval) {
-        print(interval)
+        self.timeDisplayLabel.text = String(format: "%0.02f", interval)
     }
 
 
@@ -23,6 +63,10 @@ class ViewController: UIViewController, UpdateTime {
         self.timer.startTimer()
     }
 
+    @IBAction func lapButtonPressed() {
+        self.timer.lap()
+    }
+
     func toggleButton(withTitles titles: (String, String), on button: UIButton) {
         let title = button.currentTitle == titles.0 ? titles.1 : titles.0
         button.setTitle(title, for: .normal)