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/Task/SwapUpdated.swift

@@ -0,0 +1,80 @@
+import UserNotifications
+import Foundation
+
+struct SwapUpdatedRequest: Codable {
+    let id: String
+    let status: String
+}
+
+class SwapUpdatedTask : TaskProtocol {
+    fileprivate let TAG = "SwapUpdatedTask"
+    
+    internal var payload: String
+    internal var contentHandler: ((UNNotificationContent) -> Void)?
+    internal var bestAttemptContent: UNMutableNotificationContent?
+    internal var logger: ServiceLogger
+    internal var request: SwapUpdatedRequest? = nil
+    
+    init(payload: String, logger: ServiceLogger, contentHandler: ((UNNotificationContent) -> Void)? = nil, bestAttemptContent: UNMutableNotificationContent? = nil) {
+        self.payload = payload
+        self.contentHandler = contentHandler
+        self.bestAttemptContent = bestAttemptContent
+        self.logger = logger
+    }
+    
+    func start(liquidSDK: BindingLiquidSdk) throws {
+        do {
+            self.request = try JSONDecoder().decode(SwapUpdatedRequest.self, from: self.payload.data(using: .utf8)!)
+        } catch let e {
+            self.logger.log(tag: TAG, line: "Failed to decode payload: \(e)", level: "ERROR")
+            self.onShutdown()
+            throw e
+        }
+    }
+
+    public func onEvent(e: SdkEvent) {
+        if let swapIdHash = self.request?.id {
+            switch e {
+            case .paymentSucceeded(details: let payment):
+                let swapId = self.getSwapId(details: payment.details)
+                if swapIdHash == swapId?.sha256() {
+                    self.logger.log(tag: TAG, line: "Received payment succeeded event: \(swapIdHash)", level: "INFO")
+                    self.notifySuccess(payment: payment)
+                }
+                break
+            default:
+                break
+            }
+        }
+    }
+
+    func getSwapId(details: PaymentDetails?) -> String? {
+        if let details = details {
+            switch details {
+            case let .bitcoin(swapId, _, _, _):
+                return swapId
+            case let .lightning(swapId, _, _, _, _, _):
+                return swapId
+            default:
+                break
+            }
+        }
+        return nil
+    }
+
+    func onShutdown() {
+        let notificationTitle = ResourceHelper.shared.getString(key: Constants.SWAP_CONFIRMED_NOTIFICATION_FAILURE_TITLE, fallback: Constants.DEFAULT_SWAP_CONFIRMED_NOTIFICATION_FAILURE_TITLE)
+        let notificationBody = ResourceHelper.shared.getString(key: Constants.SWAP_CONFIRMED_NOTIFICATION_FAILURE_TEXT, fallback: Constants.DEFAULT_SWAP_CONFIRMED_NOTIFICATION_FAILURE_TEXT)
+        self.displayPushNotification(title: notificationTitle, body: notificationBody, logger: self.logger, threadIdentifier: Constants.NOTIFICATION_THREAD_SWAP_UPDATED)
+    }
+
+    func notifySuccess(payment: Payment) {
+        self.logger.log(tag: TAG, line: "Payment \(payment.txId ?? "") completed successfully", level: "INFO")
+        let received = payment.paymentType == PaymentType.receive
+        let notificationTitle = ResourceHelper.shared.getString(
+            key: received ? Constants.PAYMENT_RECEIVED_NOTIFICATION_TITLE : Constants.PAYMENT_SENT_NOTIFICATION_TITLE, 
+            validateContains: "%d", 
+            fallback: received ? Constants.DEFAULT_PAYMENT_RECEIVED_NOTIFICATION_TITLE: Constants.DEFAULT_PAYMENT_SENT_NOTIFICATION_TITLE)
+        self.displayPushNotification(title: String(format: notificationTitle, payment.amountSat), logger: self.logger, threadIdentifier: Constants.NOTIFICATION_THREAD_SWAP_UPDATED)
+    }
+}