NWSAlert ExtendedInfo caching.

1Weather/Network/Notifications/NWSAlertInfoParser.swift

@@ -8,8 +8,33 @@
 import Foundation
 
 class NWSAlertInfoParser {
-    public func fetchExtendedInfo(for alert: NWSAlert, completion: @escaping (NWSAlertExtendedInfo?) -> ()) {
+    public func fetchExtendedInfo(for alert: NWSAlert, completion: @escaping (String?, NWSAlertExtendedInfo?) -> ()) {
         let log = Logger(componentName: "NWSAlertInfoParser (alert \(alert.messageID))")
+        fetchContent(for: alert, logger: log) { [weak self] (weatherMessage) in
+            guard let weatherMessage = weatherMessage else {
+                completion(nil, nil)
+                return
+            }
+            guard let self = self else { return }
+            let extendedInfo: NWSAlertExtendedInfo = self.parseExtendedInfo(from: weatherMessage)
+            let debugEncoder = JSONEncoder()
+            debugEncoder.outputFormatting = .prettyPrinted
+            debugEncoder.dateEncodingStrategy = .iso8601
+            if let jsonData = try? debugEncoder.encode(extendedInfo), let json = String(data: jsonData, encoding: .utf8) {
+                log.debug("Parsed: \(json)")
+            }
+            completion(weatherMessage, extendedInfo)
+        }
+    }
+    
+    // MARK: - Private methods
+    
+    private func fetchContent(for alert: NWSAlert, logger log: Logger, completion: @escaping (String?) -> ()) {
+        guard alert.weatherMessage == nil else {
+            log.debug("Using previously fetched weatherMessage")
+            completion(alert.weatherMessage)
+            return
+        }
         log.info("URL: \(alert.messageURL)")
         guard let url = URL(string: alert.messageURL) else {
             log.error("Bad URL")
@@ -32,19 +57,10 @@ class NWSAlertInfoParser {
                 return
             }
             log.debug("Response: \(responseString)")
-            let extendedInfo: NWSAlertExtendedInfo = self.parseExtendedInfo(from: responseString)
-            let debugEncoder = JSONEncoder()
-            debugEncoder.outputFormatting = .prettyPrinted
-            debugEncoder.dateEncodingStrategy = .iso8601
-            if let jsonData = try? debugEncoder.encode(extendedInfo), let json = String(data: jsonData, encoding: .utf8) {
-                log.debug("Parsed: \(json)")
-            }
-            completion(extendedInfo)
+            completion(responseString)
         }.resume()
     }
     
-    // MARK: - Private methods
-    
     private static var dateFormatter: DateFormatter = {
         let dateFormatter = DateFormatter()
         // Date examples:

1Weather/Network/Notifications/NWSAlertsManager.swift

@@ -161,15 +161,16 @@ public class NWSAlertsManager {
             var newAlertsToFetch = [NWSAlert]()
             
             let parser = NWSAlertInfoParser()
-            for alert in alerts {
+            for alert in alerts.filter({ $0.extendedInfo == nil }) {
                 if !self.extendedInfoBeingFetched.contains(alert) {
                     self.extendedInfoBeingFetched.insert(alert)
-                    parser.fetchExtendedInfo(for: alert) { [weak self] (extendedInfo) in
+                    parser.fetchExtendedInfo(for: alert) { [weak self] (weatherMessage, extendedInfo) in
                         DispatchQueue.main.async { [weak self] in
                             guard let self = self else { return }
                             guard let alertIndex = self.alerts.firstIndex(where: { $0 == alert }) else {
                                 return
                             }
+                            self.alerts[alertIndex].weatherMessage = weatherMessage
                             self.alerts[alertIndex].extendedInfo = extendedInfo
                             self.internalQueue.addOperation {
                                 self.extendedInfoBeingFetched.remove(alert)