How to empty an appended array after a widget timeline update - swift

Question

I am transitioning from UIKit to SwiftUI in my app and am updating network calls to async await as well. I created a Large size widget that displays the weather for 7 airports. The airports identifiers are stored in an app group shared userdefatults container. I update the timeline every minute (just for testing, normally it would be every 20 minutes). Initially when the widget is selected and appears, all data is there and correct. After a timeline update the data updates, but not all the airports are returned and after two updates or so (not consistent), the screen goes blank. The userdefaults airports are updated from the main app and saved in the shared user defaults container and it calls WidgetCenter.shared.reloadAllTimelines. This is all working fine as I have another process that uses the same container for a small widget, but with only one airport returning data without the need for an appended array. If I remove the calls to empty the array, the data remains and doesn't go blank, but of course the array keeps appending. I've tried the removeAll() and [] to empty the array at different places in the code, but same result. I am trying to understand the flow in the async/await calls, but seem to be missing something here? Any help would be greatly appreciated. I've been googling and searching stack overflow for a month and don't really know how to solve this issue. Thanks in advance!
actor MetarService: NSObject, XMLParserDelegate, URLSessionDelegate, ObservableObject {
enum MetarFetcherError: Error {
case invalidServerResponse
case missingData
}
#Published var metarArray = [String]()
#Published var metarDataModel: [MetarDataModel] = []
var tempDataModel: [MetarDataModel] = []
func fetchMetars(metarAPTs: String) async throws -> [MetarDataModel] {
let wxUrl = URL(string: "https://www.aviationweather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&hoursBeforeNow=3&mostRecent=true&stationString=" + metarAPTs)!
let (data, response) = try await URLSession.shared.data(from: wxUrl)
guard let httpResponse = response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
throw MetarFetcherError.invalidServerResponse
}
guard let xml = SWXMLHash.parse(data) as XMLIndexer? else {
throw MetarFetcherError.missingData
}
noDataResponse = (xml["response"]["data"].element?.attribute(by: "num_results")?.text) ?? "0"
if noDataResponse == "1" && (xml["response"]["data"]["METAR"]["observation_time"].element?.text) != nil {
if (xml["response"]["data"]["METAR"]["station_id"].element?.text) != nil {
myairport = xml["response"]["data"]["METAR"]["station_id"].element!.text
} else {
myairport = "MSNG"
}
if (xml["response"]["data"]["METAR"]["flight_category"].element?.text) != nil {
myfltcat = xml["response"]["data"]["METAR"]["flight_category"].element!.text
} else {
myfltcat = "MISNG"
}
switch myfltcat {
case "VFR":
mymetarImage = "sun.max.circle.fill"
case "MVFR":
mymetarImage = "cloud.sun.circle.fill"
case "IFR":
mymetarImage = "cloud.fog.circle.fill"
case "LIFR":
mymetarImage = "smoke.circle.fill"
default:
mymetarImage = "person.crop.circle.badge.questionmark"
}
if (xml["response"]["data"]["METAR"]["observation_time"].element?.text) != nil {
myobstime = xml["response"]["data"]["METAR"]["observation_time"].element!.text as NSString
if myobstime.length < 16 {
myobstime = "MISNG"
} else {
myobstime = myobstime.substring(with: NSRange(location: 11, length: 5)) as NSString
}
}
if (xml["response"]["data"]["METAR"]["visibility_statute_mi"].element?.text) != nil {
myvis = xml["response"]["data"]["METAR"]["visibility_statute_mi"].element!.text
let intVis = (myvis as NSString) .integerValue
myvis = String(intVis) + "SM"
} else {
myvis = "0"
}
if (xml["response"]["data"]["METAR"]["wind_dir_degrees"].element?.text) != nil {
mywinddir = xml["response"]["data"]["METAR"]["wind_dir_degrees"].element!.text
if mywinddir.contains("VRB") {
mywinddir = "VRB"
} else
if mywinddir.count <= 2 && mywinddir.count > 0 {
mywinddir = "0" + mywinddir
}
} else {
mywinddir = "MISNG"
}
if (xml["response"]["data"]["METAR"]["wind_speed_kt"].element?.text) != nil {
mywindspd = xml["response"]["data"]["METAR"]["wind_speed_kt"].element!.text
if mywindspd == "0" {
mywind = "Calm"
} else if mywindspd.count == 1 {
mywindspd = "0" + mywindspd
mywind = mywinddir + "/" + mywindspd + "KT"
} else if mywindspd.count > 1 {
mywind = mywinddir + "/" + mywindspd + "KT"
}
} else {
mywind = "MISNG"
}
}
self.tempDataModel.append(MetarDataModel(metarImage: mymetarImage, mairport: myairport, mobstime: myobstime as String, mfltcat: myfltcat, mvis: myvis, mwind: mywind))
self.metarDataModel = self.tempDataModel
tempDataModel = []
return metarDataModel
}
func readMetarApts() -> [String] {
let defaults = UserDefaults(suiteName: "group.userdefaults.shared.FRAT")!
if ((defaults.value(forKey: "icaoIdent") as! String).isEmpty) {
defaultairport = "KSFO"
} else {
defaultairport = defaults.value(forKey: "icaoIdent") as! String
}
wxAirport1 = defaults.value(forKey: "wxAirport1") as! String
wxAirport2 = defaults.value(forKey: "wxAirport2") as! String
wxAirport3 = defaults.value(forKey: "wxAirport3") as! String
wxAirport4 = defaults.value(forKey: "wxAirport4") as! String
wxAirport5 = defaults.value(forKey: "wxAirport5") as! String
wxAirport6 = defaults.value(forKey: "wxAirport6") as! String
metarArray.append(defaultairport)
metarArray.append(wxAirport1)
metarArray.append(wxAirport2)
metarArray.append(wxAirport3)
metarArray.append(wxAirport4)
metarArray.append(wxAirport5)
metarArray.append(wxAirport6)
metarArray = metarArray.sorted()
let returnArray = metarArray
metarArray = []
return returnArray
}// end of readAirports function
nonisolated func getAirports() -> ([MetarDataModel] ){
// transData = []
Task{
let tempArray = await readMetarApts()
for apts in tempArray {
let zData = try await self.fetchMetars(metarAPTs: apts)
if zData .isEmpty {
let errorData = MetarDataModel(metarImage: "sun.max.circle.fill", mairport: "DATA", mobstime: "CHK", mfltcat: "MSNG", mvis: "WiFi", mwind: "")
tempData = [errorData]
} else {
transData.append(contentsOf: zData)
tempData = transData
} // else Closure
} //Task Closure
//transData.removeAll()
} // apts in tempArray Closure
tempData = transData
// transData = []
return tempData.sorted()
} // end of getAirports function
} // end of MetarService Class
I have tried different solutions found on stack overflow, reddit, medium and others. But no matter what approach I take, if I try and empty the appended array in preparation for the next timeline update, it will always eventually return without data. At first I thought it was the app group shared container losing reference as I got the much debated 'kCFPreferencesAnyUser, ByHost: Yes, Container: (null)): Using kCFPreferencesAnyUser with a container is only allowed for System Containers, detaching from cfprefsd' in the log, but Apple says this does not indicate that particular condition? And, I use the container elsewhere with no issues. I am new to the async await and the new URLSession.shared.data(from: ) and maybe I'm not understanding the flow and timing of how the data is fetched and returned? I just need to append the array, display the data, then empty the array and wait for the next timeline to fetch new data. I've put the removeAll() and tried [] as an alternative in many different places in my code (at the start of the function and at the end of the function). Stumped!!