Fix the preview crash resulted from the table view scrolling quickly. (…

…#3416)

Sources/MapboxNavigation/NavigationMapView.swift

@@ -897,8 +897,7 @@ open class NavigationMapView: UIView {
      - parameter stepIndex: Zero-based index of the `RouteStep` which contains the maneuver.
      */
     public func addArrow(route: Route, legIndex: Int, stepIndex: Int) {
-        guard route.legs.indices.contains(legIndex),
-              route.legs[legIndex].steps.indices.contains(stepIndex),
+        guard route.containsStep(at: legIndex, stepIndex: stepIndex),
               let triangleImage = Bundle.mapboxNavigation.image(named: "triangle")?.withRenderingMode(.alwaysTemplate) else { return }
 
         do {

Sources/MapboxNavigation/NavigationViewController.swift

@@ -1104,6 +1104,7 @@ extension NavigationViewController: TopBannerViewControllerDelegate {
 
     public func topBanner(_ banner: TopBannerViewController, didSelect legIndex: Int, stepIndex: Int, cell: StepTableViewCell) {
         let progress = navigationService.routeProgress
+        guard progress.route.containsStep(at: legIndex, stepIndex: stepIndex) else { return }
         let legProgress = RouteLegProgress(leg: progress.route.legs[legIndex], stepIndex: stepIndex)
         let step = legProgress.currentStep
         self.preview(step: step, in: banner, remaining: progress.remainingSteps, route: progress.route)

Sources/MapboxNavigation/Route.swift

@@ -155,6 +155,13 @@ extension Route {
             return LineString(coordinateList)
         }
     }
+
+    /**
+     Returns true if both the legIndex and stepIndex are valid in the route.
+     */
+    func containsStep(at legIndex: Int, stepIndex: Int) -> Bool {
+        return legs[safe: legIndex]?.steps.indices.contains(stepIndex) ?? false
+    }
 }
 
 extension RouteStep {

Sources/MapboxNavigation/StepsViewController.swift

@@ -192,18 +192,23 @@ public class StepsViewController: UIViewController {
 extension StepsViewController: UITableViewDelegate {
     public func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
         tableView.deselectRow(at: indexPath, animated: true)
+        let legIndex = indexPath.section
         let cell = tableView.cellForRow(at: indexPath) as! StepTableViewCell
         // Since as we progress, steps are removed from the list, we need to map the row the user tapped to the actual step on the leg.
         // If the user selects a step on future leg, all steps are going to be there.
         var stepIndex: Int
-        if indexPath.section > 0 {
+        if legIndex > 0 {
             stepIndex = indexPath.row
         } else {
             stepIndex = indexPath.row + routeProgress.currentLegProgress.stepIndex
             // For the current leg, we need to know the upcoming step.
-            stepIndex += indexPath.row + 1 > sections[indexPath.section].count ? 0 : 1
+            if sections[legIndex].indices.contains(indexPath.row) {
+                stepIndex += 1
+            }
         }
-        delegate?.stepsViewController(self, didSelect: indexPath.section, stepIndex: stepIndex, cell: cell)
+
+        guard routeProgress.route.containsStep(at: legIndex, stepIndex: stepIndex) else { return }
+        delegate?.stepsViewController(self, didSelect: legIndex, stepIndex: stepIndex, cell: cell)
     }
 }
 

Tests/MapboxNavigationTests/RouteTests.swift

@@ -78,4 +78,20 @@ class RouteTests: TestCase {
             XCTAssertLessThan(lastIndexedCoordinate!.coordinate.distance(to: maneuverPolyline.coordinates.last!), 1, "End of maneuver polyline for step \(stepIndex) is \(lastIndexedCoordinate!.coordinate.distance(to: maneuverPolyline.coordinates.last!)) away from outlet from intersection.")
         }
     }
+
+    func testContainsStep() {
+        guard let route = response.routes?.first else {
+            XCTFail("Failed to get route.")
+            return
+        }
+
+        var legIndex = route.legs.count - 1
+        var stepsIndex = route.legs[legIndex].steps.count
+        XCTAssertFalse(route.containsStep(at: legIndex, stepIndex: stepsIndex), "Failed to check the step index when it's larger than or equal to the steps count.")
+
+        legIndex = route.legs.count
+        stepsIndex = 0
+        XCTAssertFalse(route.containsStep(at: legIndex, stepIndex: stepsIndex), "Failed to check the leg index when it's larger than or equal to the legs count.")
+
+    }
 }