Nssortdescriptor Sorting Using Nsdate in Swift

NSSortDescriptor sorting using NSDate in Swift

// newest first
request.sortDescriptors = [NSSortDescriptor(key: "date", ascending: false)]

NB: You do not need : [NSManagedObject] if you already have as [NSManagedObject].

You do not need : NSFetchRequest when you use the factory method of NSFetchRequest.

Sort NSSortDescriptor by Month of date. Swift

You can create a custom sort to get your dates sorted by incoming birthday and pass your collection sorted to your ForEach method:

extension Collection where Element == Birthday {
    func sortedByIncomingBirthday() -> [Element] {
        sorted {
            // lhs date is today or is in the future
            ($0.date.month, $0.date.day) >= (Date().month, Date().day) ?
                // rhs date is today or is in the future
                ($1.date.month, $1.date.day) >= (Date().month, Date().day) ?
                    // sort them by a month day order
                    ($0.date.month, $0.date.day) < ($1.date.month, $1.date.day) :
                    // otherwise is in increasing order
                    true :
            // lhs date is in the past
            // sort them by a month day order
            ($0.date.month, $0.date.day) < ($1.date.month, $1.date.day)
        }
    }
}

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ForEach(birthdays.sortedByIncomingBirthday(), id: \.self) { birthday in

Another option is to extend Birthday and add a nextBirthday property this way you can sort it using it as a keyPath for your NSSortDescriptor:

extension Date {
    var isInToday: Bool { Calendar.current.isDateInToday(self) }
    var nextBirthday: Date {
        isInToday ? self : Calendar.current.nextDate(after: Date(), matching: Calendar.current.dateComponents([.month, .day, .hour, .minute], from: self), matchingPolicy: .nextTime)!
    }
}

---

extension Birthday {
    var nextBirthday: Date { date.nextBirthday }
}

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NSSortDescriptor(keyPath: \Birthday.nextBirthday, ascending: true)

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edit/update:

if Birthday date property is optional don't force unwrap its value:

extension Birthday {
    var nextBirthday: Date { date?.nextBirthday ?? .distantFuture }
}

and the first approach would need to deal with it as well:

extension Collection where Element == Birthday {
    func sortedByIncomingBirthday() -> [Element] {
        sorted { lhs, rhs in
            if lhs.date == nil { return false }
            let lhs = lhs.date ?? .distantFuture
            let rhs = rhs.date ?? .distantFuture
            // lhs date is today or is in the future
            return (lhs.month, lhs.day) >= (Date().month, Date().day) ?
                       // rhs date is today or is in the future
                       (rhs.month, rhs.day) >= (Date().month, Date().day) ?
                           // sort them by a month day order
                           (lhs.month, lhs.day) < (rhs.month, rhs.day) :
                           // otherwise is in increasing order
                           true :
                   // lhs date is in the past
                   // sort them by a month day order
                   (lhs.month, lhs.day) < (rhs.month, rhs.day)
        }
    }
}

NSSortDescriptor NSDate ascending. How to sort objects with the same date?

sortDescriptors is an array, so add additional NSSortDescriptor for the second property you wish, something like that:

eventsRequest.sortDescriptors = [NSSortDescriptor(key: "startDate", ascending: true), NSSortDescriptor(key: "eventType", ascending: true)]

This will firstly use NSSortDescriptor for the startDate and if they are the same will check value of eventType

Core Data sort descriptor with NSDate, iOS with Swift

To fetch all objects satisfying some condition you don't need a
sort descriptor but a predicate, for example:

let predicate = NSPredicate(format: "timeStamp < %@", date)
fetchRequest.predicate = predicate

You need a sort descriptor to get the objects in a specified order,
for example:

let sectionSortDescriptor = NSSortDescriptor(key: "timeStamp", ascending: true)
let sortDescriptors = [sectionSortDescriptor]
fetchRequest.sortDescriptors = sortDescriptors

Multiple NSSortDescriptor Not Working When The 1st Descriptor is NSDate

I finally figured it out:

Apparently it's the sub-seconds information that also being saved into Core Data making the comparison between dates (even though the dates being compared share the exact same date) not working.

So what I did was to remove the sub-seconds information before saving it to Core Data:

self.recordDate = [NSDate dateWithTimeIntervalSinceReferenceDate:floor([recordDate timeIntervalSinceReferenceDate])];

I hope this can help anyone facing the same problem. Cheers!

NSSortDescriptor using NSDate attribute of Entity (Swift)

You can sort by setting a sortDescriptor on the NSFetchRequest. Pass true or false depending on if you want the results to be acending or descending.

var fetchRequest = NSFetchRequest(entityName: "Assessment")
fetchRequest.sortDescriptors = [NSSortDescriptor(key: "nsDateOfAssessment", ascending: false)]

You could then use a high order function to map the results to only get the weight attribute you want

let fetchedResults = managedContext.executeFetchRequest(fetchRequest, error: &error) as [Assessment]?

Notice how I'm setting it to be an array of your subclassed NSManagedObject

if let assessments = fetchedResults {
   let weights = assessments.map { assessment in assessment.weight }
}

Set NSSortDescriptor for CoreData using a calculated field

Unfortunately, it appears that this is not possible. A Core Data fetch request cannot sort on a computed property, only on persistent stored properties. I found the following question that I had previously overlooked on this site.

Sorting NSFetchedResultsController by Swift Computed Property on NSManagedObjectSubclass

However, if anyone knows otherwise, please let me know.

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