Swift notification plugin (#436)

* Add Swift notification plugin

* Hash the metadata

* Validate min sendable amount

* Remove initializer as base class, UNNotificationServiceExtension, has no default initializer

* Set the PaymentMethod

* Handle PaymentDetails in SwapUpdated

* Improve payment text

lib/bindings/langs/swift/Sources/BreezSDKLiquid/SDKNotificationService.swift

@@ -0,0 +1,94 @@
+import UserNotifications
+import os.log
+
+open class SDKNotificationService: UNNotificationServiceExtension {
+    fileprivate let TAG = "SDKNotificationService"
+    
+    var liquidSDK: BindingLiquidSdk?
+    var contentHandler: ((UNNotificationContent) -> Void)?
+    var bestAttemptContent: UNMutableNotificationContent?
+    var currentTask: TaskProtocol?
+    public var logger: ServiceLogger = ServiceLogger(logStream: nil)
+    
+    override public init() { }
+
+    override open func didReceive(
+        _ request: UNNotificationRequest,
+        withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void
+    ) {
+        self.logger.log(tag: TAG, line: "Notification received", level: "INFO")
+        self.contentHandler = contentHandler
+        self.bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
+                
+        guard let connectRequest = self.getConnectRequest() else {
+            if let content = bestAttemptContent {
+                contentHandler(content)
+            }
+            return
+        }
+        
+        if let currentTask = self.getTaskFromNotification() {
+            self.currentTask = currentTask
+            
+            DispatchQueue.main.async { [self] in
+                do {
+                    logger.log(tag: TAG, line: "Breez Liquid SDK is not connected, connecting...", level: "INFO")
+                    liquidSDK = try BreezSDKLiquidConnector.register(connectRequest: connectRequest, listener: currentTask)
+                    logger.log(tag: TAG, line: "Breez Liquid SDK connected successfully", level: "INFO")
+                    try currentTask.start(liquidSDK: liquidSDK!)
+                } catch {
+                    logger.log(tag: TAG, line: "Breez Liquid SDK connection failed \(error)", level: "ERROR")
+                    shutdown()
+                }
+            }
+        }
+    }
+    
+    open func getConnectRequest() -> ConnectRequest? {
+        return nil
+    }
+        
+    open func getTaskFromNotification() -> TaskProtocol? {
+        guard let content = bestAttemptContent else { return nil }
+        guard let notificationType = content.userInfo[Constants.MESSAGE_DATA_TYPE] as? String else { return nil }
+        self.logger.log(tag: TAG, line: "Notification payload: \(content.userInfo)", level: "INFO")
+        self.logger.log(tag: TAG, line: "Notification type: \(notificationType)", level: "INFO")
+        
+        guard let payload = content.userInfo[Constants.MESSAGE_DATA_PAYLOAD] as? String else {
+            contentHandler!(content)
+            return nil
+        }
+        
+        self.logger.log(tag: TAG, line: "\(notificationType) data string: \(payload)", level: "INFO")
+        switch(notificationType) {
+        case Constants.MESSAGE_TYPE_SWAP_UPDATED:
+            return SwapUpdatedTask(payload: payload, logger: self.logger, contentHandler: contentHandler, bestAttemptContent: bestAttemptContent)
+        case Constants.MESSAGE_TYPE_LNURL_PAY_INFO:
+            return LnurlPayInfoTask(payload: payload, logger: self.logger, contentHandler: contentHandler, bestAttemptContent: bestAttemptContent)
+        case Constants.MESSAGE_TYPE_LNURL_PAY_INVOICE:
+            return LnurlPayInvoiceTask(payload: payload, logger: self.logger, contentHandler: contentHandler, bestAttemptContent: bestAttemptContent)
+        default:
+            return nil
+        }
+    }
+    
+    override open func serviceExtensionTimeWillExpire() {
+        self.logger.log(tag: TAG, line: "serviceExtensionTimeWillExpire()", level: "INFO")
+        
+        // iOS calls this function just before the extension will be terminated by the system.
+        // Use this as an opportunity to deliver your "best attempt" at modified content,
+        // otherwise the original push payload will be used.
+        self.shutdown()
+    }
+    
+    private func shutdown() -> Void {
+        self.logger.log(tag: TAG, line: "shutting down...", level: "INFO")
+        BreezSDKLiquidConnector.unregister()
+        self.logger.log(tag: TAG, line: "task unregistered", level: "INFO")
+        self.currentTask?.onShutdown()
+    }
+    
+    public func setLogger(logger: Logger) {
+        self.logger = ServiceLogger(logStream: logger)
+    }
+}