Swift How to Return from Function - swift

Question

I can't find a way to have the makeQuery() function return the summary result. How do I do this? I want to be able to call makeQuery() and have it return summary. summary is an object holding some data. HKActivitySummary to be specific.
func makeQuery() {
let calendar = NSCalendar.current
let endDate = Date()
guard let startDate = calendar.date(byAdding: .day, value: 0, to: endDate) else {
fatalError("error")
}
let units: Set<Calendar.Component> = [.day, .month, .year, .era]
var startDatecomps = calendar.dateComponents(units, from: startDate)
startDatecomps.calendar = calendar
var endDatecomps = calendar.dateComponents(units, from: endDate)
endDatecomps.calendar = calendar
let summariesWithinRange = HKQuery.predicate(
forActivitySummariesBetweenStart: startDatecomps, end: endDatecomps)
let query = HKActivitySummaryQuery(predicate: summariesWithinRange) {
(sample, results, error) -> Void in
if let results = results {
if let summary = results.first {
print(summary) // how to have makeQuery() return the summary value? Just printing it to the console right now to confirm data is being retrieved
}
}
}
healthstore.execute(query)
}