iOS: UICollectionView sections from array with dates

Question

I have an array of Person. The Person object has many fields between them inscriptionDate (a timestamp). I have to create a collectionView from this array but using sections. Every section has a header that is inscriptionDate as a date having this format dd/mm/yyyy. I have to sort the array by inscriptionDate but without time (only the format dd/mm/yyyy) in order to load the data in the collectionView (taking into consideration the sections). I have found from another question this solution. But how can I sort the array before doing this? How can I use this:

order = NSCalendar.currentCalendar().compareDate(now, toDate: olderDate, 
            toUnitGranularity: .Day)

in my case?

Answer 1

First, you'll need to clean timestamp before the sorting. You can do that by using Calendar and Date extension:

extension Date {
    func noTime() -> Date! {
        let components = Calendar.current.dateComponents([.day, .month, .year], from: self)
        return Calendar.current.date(from: components)
    }
}

Then you'll just need to sort your array by date without time:

let sortedByDate = persons.sorted { $0.inscriptionDate.noTime() < $1.inscriptionDate.noTime() }

Note. Be careful with compareDate function of Calendar, since it comparing only specific component. If in this example: NSCalendar.currentCalendar().compareDate(now, toDate: olderDate, toUnitGranularity: .Day) you'll have same days in different months, the comparing result will show that dates are equal.