You can use Calendar
‘s dateComponents(_:from:to:)
to find the difference between 2 dates to your desired units.
Example:
let dateRangeStart = Date()
let dateRangeEnd = Date().addingTimeInterval(12345678)
let components = Calendar.current.dateComponents([.weekOfYear, .month], from: dateRangeStart, to: dateRangeEnd)
print(dateRangeStart)
print(dateRangeEnd)
print("difference is \(components.month ?? 0) months and \(components.weekOfYear ?? 0) weeks")
> 2017-02-17 10:05:19 +0000
> 2017-07-10 07:26:37 +0000
> difference is 4 months and 3 weeks
let months = components.month ?? 0
let weeks = components.weekOfYear ?? 0