Add scroll changed event

Sources/Core/ScreenViewTracking/ScreenSummaryState.swift

@@ -22,14 +22,18 @@ class ScreenSummaryState: State {
     var backgroundSeconds: TimeInterval = 0
     var lastItemIndex: Int?
     var itemsCount: Int?
+    var maxYOffset: Int?
+    var contentHeight: Int?
 
     var data: [String: Any] {
         var data: [String: Any] = [
-            "foreground_sec": foregroundSeconds,
-            "background_sec": backgroundSeconds
+            "foreground_sec": round(foregroundSeconds * 100) / 100,
+            "background_sec": round(backgroundSeconds * 100) / 100
         ]
         if let lastItemIndex = lastItemIndex { data["last_item_index"] = lastItemIndex }
         if let itemsCount = itemsCount { data["items_count"] = itemsCount }
+        if let maxYOffset = maxYOffset { data["max_y_offset"] = maxYOffset }
+        if let contentHeight = contentHeight { data["content_height"] = contentHeight }
         return data
     }
 
@@ -60,5 +64,10 @@ class ScreenSummaryState: State {
             self.itemsCount = max(totalItems, self.itemsCount ?? 0)
         }
     }
+
+    func updateWithScrollChanged(_ event: ScrollChanged) {
+        maxYOffset = max(event.yOffset, maxYOffset ?? 0)
+        contentHeight = max(event.contentHeight, contentHeight ?? 0)
+    }
 
 }

Sources/Core/ScreenViewTracking/ScreenSummaryStateMachine.swift

@@ -22,7 +22,7 @@ class ScreenSummaryStateMachine: StateMachineProtocol {
     }
 
     var subscribedEventSchemasForTransitions: [String] {
-        return [kSPScreenViewSchema, kSPScreenEndSchema, kSPForegroundSchema, kSPBackgroundSchema, kSPListItemViewSchema]
+        return [kSPScreenViewSchema, kSPScreenEndSchema, kSPForegroundSchema, kSPBackgroundSchema, kSPListItemViewSchema, kSPScrollChangedSchema]
     }
 
     var subscribedEventSchemasForEntitiesGeneration: [String] {
@@ -38,7 +38,7 @@ class ScreenSummaryStateMachine: StateMachineProtocol {
     }
 
     var subscribedEventSchemasForFiltering: [String] {
-        return [kSPListItemViewSchema, kSPScreenEndSchema]
+        return [kSPListItemViewSchema, kSPScrollChangedSchema, kSPScreenEndSchema]
     }
 
     func eventsBefore(event: Event) -> [Event]? {
@@ -59,6 +59,8 @@ class ScreenSummaryStateMachine: StateMachineProtocol {
                 state.updateForScreenEnd()
             case let itemView as ListItemView:
                 state.updateWithListItemView(itemView)
+            case let scrollChanged as ScrollChanged:
+                state.updateWithScrollChanged(scrollChanged)
             default:
                 break
             }
@@ -82,7 +84,7 @@ class ScreenSummaryStateMachine: StateMachineProtocol {
         if event.schema == kSPScreenEndSchema {
             return state != nil
         }
-        // do not track list item view events
+        // do not track list item view or scroll changed events
         return false
     }
 

Sources/Core/TrackerConstants.swift

@@ -73,6 +73,7 @@ let ecommercePageSchema = "iglu:com.snowplowanalytics.snowplow.ecommerce/page/js
 let kSPScreenEndSchema = "iglu:com.snowplowanalytics.mobile/screen_end/jsonschema/1-0-0"
 let kSPScreenSummarySchema = "iglu:com.snowplowanalytics.mobile/screen_summary/jsonschema/1-0-0"
 let kSPListItemViewSchema = "iglu:com.snowplowanalytics.mobile/list_item_view/jsonschema/1-0-0"
+let kSPScrollChangedSchema = "iglu:com.snowplowanalytics.mobile/scroll_changed/jsonschema/1-0-0"
 
 // --- Event Keys
 let kSPEventPageView = "pv"

Sources/Snowplow/Events/ListItemView.swift

@@ -25,11 +25,16 @@ public class ListItemView: SelfDescribingAbstract {
     /// Total number of items in the list
     public var itemsCount: Int?
 
+    /// - Parameters:
+    ///   - index: Index of the item in the list
     @objc
     public init(index: Int) {
         self.index = index
     }
 
+    /// - Parameters:
+    ///   - index: Index of the item in the list
+    ///   - totalItems: Total number of items in the list
     @objc
     public init(index: Int, totalItems: Int) {
         self.index = index

Sources/Snowplow/Events/ScrollChanged.swift

@@ -0,0 +1,47 @@
+// Copyright (c) 2013-2023 Snowplow Analytics Ltd. All rights reserved.
+//
+// This program is licensed to you under the Apache License Version 2.0,
+// and you may not use this file except in compliance with the Apache License
+// Version 2.0. You may obtain a copy of the Apache License Version 2.0 at
+// http://www.apache.org/licenses/LICENSE-2.0.
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the Apache License Version 2.0 is distributed on
+// an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the Apache License Version 2.0 for the specific
+// language governing permissions and limitations there under.
+
+import Foundation
+
+/// Event tracked when a scroll view's scroll position changes.
+/// If screen engagement tracking is enabled, the scroll changed events will be aggregated into a `screen_summary` entity.
+///
+/// Schema: `iglu:com.snowplowanalytics.mobile/scroll_changed/jsonschema/1-0-0`
+@objc(SPScrollChanged)
+public class ScrollChanged: SelfDescribingAbstract {
+    /// Vertical scroll offset in pixels
+    @objc
+    public var yOffset: Int
+    /// The height of the scroll view content in pixels
+    public var contentHeight: Int
+
+    /// - Parameters:
+    ///   - yOffset: Vertical scroll offset in pixels
+    ///   - contentHeight: The height of the scroll view content in pixels
+    @objc
+    public init(yOffset: Int, contentHeight: Int) {
+        self.yOffset = yOffset
+        self.contentHeight = contentHeight
+    }
+
+    override var schema: String {
+        return kSPScrollChangedSchema
+    }
+
+    override var payload: [String : Any] {
+        return [
+            "y_offset": yOffset,
+            "content_height": contentHeight
+        ]
+    }
+}

Tests/ScreenViewTracking/TestScreenSummaryStateMachine.swift

@@ -101,6 +101,29 @@ class TestScreenSummaryStateMachine: XCTestCase {
 
         wait(for: [expectScreenEnd], timeout: 10)
     }
+
+    func testUpdatesScrollMetrics() {
+        let expectScreenEnd = expectation(description: "Screen end event")
+
+        let eventSink = EventSink { event in
+            if event.schema == kSPScreenEndSchema {
+                let entity = event.entities.first { $0.schema == kSPScreenSummarySchema }
+                XCTAssertEqual((entity?.data as? [String: Any])?["max_y_offset"] as? Int, 30)
+                XCTAssertEqual((entity?.data as? [String: Any])?["content_height"] as? Int, 100)
+                expectScreenEnd.fulfill()
+            }
+        }
+
+        let tracker = createTracker([eventSink])
+
+        _ = tracker.track(ScreenView(name: "Screen 1"))
+        _ = tracker.track(ScrollChanged(yOffset: 10, contentHeight: 100))
+        _ = tracker.track(ScrollChanged(yOffset: 30, contentHeight: 100))
+        _ = tracker.track(ScrollChanged(yOffset: 20, contentHeight: 100))
+        _ = tracker.track(ScreenView(name: "Screen 2"))
+
+        wait(for: [expectScreenEnd], timeout: 10)
+    }
 
     private func createTracker(_ configurations: [ConfigurationProtocol]) -> TrackerController {
         let networkConfig = NetworkConfiguration(networkConnection: MockNetworkConnection(requestOption: .post, statusCode: 200))