Swift 2d array empty after HealthKit function call - thread issues - ios

Question

I'm populating a twodimensional array with HealthKit data. It's working fine as long as the function loops through the 30 days. outside of that function the array is empty because HealthKit data is loaded in background and everything else executes before.
How can I wait until the data is loaded so I can access the data inside the arrays?
Here's what's happening inside my ViewController
print("function call starting") // 1
// Populate 2DArrays
self.hkManager.getTotalCalories(forDay: 30) {caloriesValue, date in
//check if caloriesValue is nil, only do something if it's not
guard let caloriesValue = caloriesValue else { return }
let dateValue = DateFormatter.localizedString(from: date!, dateStyle: .short, timeStyle: .none)
print("will append") // 7 (31x)
self.caloriesArray.append([(dateValue,caloriesValue)])
}
print("function call done") // 2
print(self.caloriesArray.count) // 3
hkManager.getWeightData(forDay: 30) {bodyMassValue, date in
// Check if bodyMassValue is nil, only do something, if it's not
guard let bodyMassValue = bodyMassValue else { return }
let dateValue = DateFormatter.localizedString(from: date!, dateStyle: .short, timeStyle: .none)
self.bodyMassArray.append([(dateValue,bodyMassValue)])
}
do {
self.age = try hkManager.getAge()
} catch let error {
print("Error calculating age: \(error)")
}
print(bodyMassArray) // 4
print(caloriesArray) // 5
print(age!) // 6
}
I've added numbers behind the print statements to make clear what get's executed when.
The functions I'm calling look like this:
func getTotalCalories(forDay days: Int, completion: #escaping ((_ calories: Int?, _ date: Date?) -> Void)) {
// Getting quantityType as .dietaryCaloriesConsumed
guard let calories = HKObjectType.quantityType(forIdentifier: .dietaryEnergyConsumed) else {
print("*** Unable to create a dietaryEnergyConsumed type ***")
return
}
let now = Date()
let startDate = Calendar.current.date(byAdding: DateComponents(day: -days), to: now)!
var interval = DateComponents()
interval.day = 1
var anchorComponents = Calendar.current.dateComponents([.day, .month, .year], from: now)
anchorComponents.hour = 0
let anchorDate = Calendar.current.date(from: anchorComponents)!
let query = HKStatisticsCollectionQuery(quantityType: calories,
quantitySamplePredicate: nil,
options: [.cumulativeSum],
anchorDate: anchorDate,
intervalComponents: interval)
query.initialResultsHandler = { _, results, error in
guard let results = results else {
print("ERROR")
return
}
results.enumerateStatistics(from: startDate, to: now) { statistics, _ in
DispatchQueue.main.async {
if let sum = statistics.sumQuantity() {
let calories = Int(sum.doubleValue(for: HKUnit.kilocalorie()).rounded())
completion(calories, statistics.startDate)
return
}
}
}
}
healthStore.execute(query)
}
Anyone any ideas what I need to do?
Thanks! :)