chore: add onOpen callback to realtime in swift/apple

Author: ChiragAgg5k

templates/swift/Sources/Services/Realtime.swift.twig

@@ -25,6 +25,7 @@ open class Realtime : Service {
 
     private var onErrorCallbacks: [((Swift.Error?, HTTPResponseStatus?) -> Void)] = []
     private var onCloseCallbacks: [(() -> Void)] = []
+    private var onOpenCallbacks: [(() -> Void)] = []
 
     public func onError(_ callback: @escaping (Swift.Error?, HTTPResponseStatus?) -> Void) {
         self.onErrorCallbacks.append(callback)
@@ -33,6 +34,10 @@ open class Realtime : Service {
     public func onClose(_ callback: @escaping () -> Void) {
         self.onCloseCallbacks.append(callback)
     }
+    
+    public func onOpen(_ callback: @escaping () -> Void) {
+        self.onOpenCallbacks.append(callback)
+    }
 
     private func startHeartbeat() {
         stopHeartbeat()
@@ -202,6 +207,7 @@ extension Realtime: WebSocketClientDelegate {
 
     public func onOpen(channel: Channel) {
         self.reconnectAttempts = 0
+        onOpenCallbacks.forEach { $0() }
         startHeartbeat()
     }