Swift - Check two arrays are they have same day without looping in a loop - swift

Question

I have 2 arrays [Date]
First is with myDates:[Date]
Second is with coreDataDates:[Date]
I'm going to for loop the second array with Core Data Dates
How to check in the loop is the DAY of myDates existing in coreDataDates ?
I know that, I can use the function NSCalendar isDate(_:inSameDayAs:), but is there a function that I don't need to loop myDates:[Date] in the coreDataDates:[Date] for loop?
Newbie example:
for date1 in coreDataDates{
for date2 in myDates{
if(Calendar.current.isDate(date1, inSameDayAs: date2)==true){
//have it
}else{
//don't have it
}
}
}
I need code that I don't have to use loop in the loop

Answer 1

If you don't care about time, Apple recommends that you set the time to noon because every day has a noon but not a midnight due to clock changes for daylight saving time.
Convert all dates in the two arrays to noon and then find the union of the two sets:
import Foundation
extension Date {
var noon: Date {
return Calendar.current.date(bySettingHour: 12, minute: 0, second: 0, of: self)!
}
}
let myDates = [
DateComponents(calendar: .current, year: 2018, month: 12, day: 1, hour: 1).date!,
DateComponents(calendar: .current, year: 2018, month: 12, day: 2, hour: 2).date!,
DateComponents(calendar: .current, year: 2018, month: 12, day: 4, hour: 3).date!
]
let coreDataDates = [
DateComponents(calendar: .current, year: 2018, month: 12, day: 1, hour: 4).date!,
DateComponents(calendar: .current, year: 2018, month: 12, day: 3, hour: 5).date!,
DateComponents(calendar: .current, year: 2018, month: 12, day: 4, hour: 6).date!
]
let myDateSet = Set(myDates.map { $0.noon })
let coreDataDateSet = Set(coreDataDates.map { $0.noon })
let commonDateSet = myDateSet.intersection(coreDataDateSet)
print(commonDateSet)

Answer 2

You can use the power of the Set class
let dateSet = Set(myDates)
let common = dateSet.intersection(coreDataDates)
//If you want it as an array
let commonDatesArray = Array(common)
See the documentation for the Set class for more info.

Answer 3

Something like:
let date1 = Date(timeIntervalSince1970: 1544019937)
let date2 = Date(timeIntervalSince1970: 1544019936)
let date3 = Date(timeIntervalSince1970: 1544019935)
let date4 = Date(timeIntervalSince1970: 1544019934)
let date5 = Date(timeIntervalSince1970: 1544019933)
let date6 = Date(timeIntervalSince1970: 1544019932)
let arr1 = [date1, date2, date3]
let arr2 = [date4, date5, date6]
print(arr2.filter { arr1.contains($0) }.count > 0 ) // false
let arr1 = [date1, date2, date3]
let arr2 = [date1, date5, date6]
print(arr2.filter { arr1.contains($0) }.count > 0 ) // true