feat: Implement Rokt event handling in iOS Flutter wrapper SDK

Signed-off-by: Thomson Thomas <thomson.thomas@rokt.com>

Author: thomson-t

ios/Classes/RoktEventHandler.swift

@@ -0,0 +1,107 @@
+//
+//  RoktEventHandler.swift
+//  rokt_sdk
+//
+//  Copyright 2020 Rokt Pte Ltd
+//
+//  Licensed under the Rokt Software Development Kit (SDK) Terms of Use
+//  Version 2.0 (the "License");
+//
+//  You may not use this file except in compliance with the License.
+//
+//  You may obtain a copy of the License at https://rokt.com/sdk-license-2-0/
+
+import Foundation
+import Flutter
+import mParticle_Apple_SDK
+
+class RoktEventHandler: NSObject, FlutterStreamHandler {
+
+    private var eventListeners: [String: [FlutterEventSink]] = [:]
+    private let EVENT_CHANNEL_NAME = "MPRoktEvents"
+
+    init(messenger: FlutterBinaryMessenger) {
+        super.init()
+        setupEventChannel(messenger: messenger)
+    }
+
+    private func setupEventChannel(messenger: FlutterBinaryMessenger) {
+        let eventChannel = FlutterEventChannel(name: EVENT_CHANNEL_NAME, binaryMessenger: messenger)
+        eventChannel.setStreamHandler(self)
+    }
+
+    func onListen(withArguments arguments: Any?, eventSink: @escaping FlutterEventSink) -> FlutterError? {
+        let key = String(describing: arguments ?? "nil")
+        var sinks = eventListeners[key] ?? []
+        sinks.append(eventSink)
+        eventListeners[key] = sinks
+        return nil
+    }
+
+    func onCancel(withArguments arguments: Any?) -> FlutterError? {
+        let key = String(describing: arguments ?? "nil")
+        if var sinks = eventListeners[key], !sinks.isEmpty {
+            sinks.removeLast()
+            if sinks.isEmpty {
+                eventListeners.removeValue(forKey: key)
+            } else {
+                eventListeners[key] = sinks
+            }
+        }
+        return nil
+    }
+
+
+    func subscribeToEvents(identifier: String) {
+        MParticle.sharedInstance().rokt.events(identifier) { event in
+            var params: [String: String] = [:]
+
+            params["event"] = String(describing: type(of: event)).replacingOccurrences(of: "MPRokt", with: "").replacingOccurrences(of: "Event", with: "")
+            params["identifier"] = identifier
+
+            if let placementId = event.roktPlacementId {
+                params["placementId"] = placementId
+            }
+            
+            switch event {
+            case let initCompleteEvent as MPRoktInitCompleteEvent:
+                params["status"] = initCompleteEvent.success ? "true" : "false"
+            case let openUrlEvent as MPRoktOpenUrlEvent:
+                params["url"] = openUrlEvent.url
+            case let cartItemInstantPurchaseEvent as MPRoktCartItemInstantPurchaseEvent:
+                params["cartItemId"] = cartItemInstantPurchaseEvent.cartItemId
+                params["catalogItemId"] = cartItemInstantPurchaseEvent.catalogItemId
+                params["currency"] = cartItemInstantPurchaseEvent.currency
+                params["description"] = cartItemInstantPurchaseEvent.cartItemDescription
+                params["linkedProductId"] = cartItemInstantPurchaseEvent.linkedProductId
+                params["totalPrice"] = cartItemInstantPurchaseEvent.totalPrice.stringValue
+                params["quantity"] = cartItemInstantPurchaseEvent.quantity.stringValue
+                params["unitPrice"] = cartItemInstantPurchaseEvent.unitPrice.stringValue
+            default:
+                break
+            }
+
+            eventListeners.values.joined().forEach { listener in
+                listener(params)
+            }
+        }
+    }
+}
+
+private extension MPRoktEvent {
+    var roktPlacementId: String? {
+        switch self {
+        case let event as MPRokt.FirstPositiveEngagement: return event.placementId
+        case let event as MPRokt.OfferEngagement: return event.placementId
+        case let event as MPRokt.PlacementClosed: return event.placementId
+        case let event as MPRokt.PlacementCompleted: return event.placementId
+        case let event as MPRokt.PlacementFailure: return event.placementId
+        case let event as MPRokt.PlacementInteractive: return event.placementId
+        case let event as MPRokt.PlacementReady: return event.placementId
+        case let event as MPRokt.PositiveEngagement: return event.placementId
+        case let event as MPRokt.OpenUrl: return event.placementId
+        case let event as MPRokt.CartItemInstantPurchase: return event.placementId
+        default: return nil
+        }
+    }
+}

ios/Classes/SwiftMparticleFlutterSdkPlugin.swift

@@ -8,11 +8,13 @@ public class SwiftMparticleFlutterSdkPlugin: NSObject, FlutterPlugin {
   let roktLayoutFactory: RoktLayoutFactory
   let channel: FlutterMethodChannel
   let registrar: FlutterPluginRegistrar
+  private let roktEventHandler: RoktEventHandler
 
   init(messenger: FlutterBinaryMessenger, registrar: FlutterPluginRegistrar) {
     self.roktLayoutFactory = RoktLayoutFactory(messenger: messenger)
     self.registrar = registrar
     self.channel = FlutterMethodChannel(name: "mparticle_flutter_sdk", binaryMessenger: messenger)
+    self.roktEventHandler = RoktEventHandler(messenger: messenger)
   }
 
   public static func register(with registrar: FlutterPluginRegistrar) {
@@ -537,7 +539,8 @@ public class SwiftMparticleFlutterSdkPlugin: NSObject, FlutterPlugin {
                 registerPartnerFonts(typefaces)
             }
 
-            MParticle.sharedInstance().rokt.selectPlacements(placementId, attributes: attributes, placements: placeholders, config: roktConfig, callbacks: callback)
+            roktEventHandler.subscribeToEvents(identifier: placementId)
+            MParticle.sharedInstance().rokt.selectPlacements(placementId, attributes: attributes, embeddedViews: placeholders, config: roktConfig, callbacks: callback)
             result(true)
         } else {
             print("Incorrect argument for \(call.method) iOS method")