CODEWITHSUNDEEP
swiftcore-datanspredicatensfetchedresultscontroller
user9599273
user9599273

Reputation:

Check Core Data for an entry with Today's Date & perform function

I am fairly new to Swift & hoping someone knows the answer to this - nothing I try seems to work!

I have a Swift app which has a Core Data entity called "Drink" with 2 keys: a Date & then one called "drinkWater" which stores a value of "1" when a button is pushed.

I am trying to write a separate function where I can check if an entry exists for todays date and, if so, perform an action (in this case change an imageview).

I realise the below isn't the answer but it's as far as I got! Basically I can get all of the entries based on the value of drinkWater (this would need to be by Date I am guessing?) and I can get today's date all printing to the console. Now I'm stuck ...

private func updateMyImageView() {

    let appDelegate = UIApplication.shared.delegate as! AppDelegate

    let context = appDelegate.persistentContainer.viewContext

    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Drink")
    request.predicate = NSPredicate(format: "drinkWater = %@", "1")
    request.returnsObjectsAsFaults = false

    do {
        let result = try context.fetch(request)
        for data in result as! [NSManagedObject] {
            print(data.value(forKey: "timestamp") as! Date)

        }

    } catch {

        print("Failed")
    }

    let dateNow = Date()

    print("Date is \(dateNow)")

}

This returns:

2018-12-29 01:27:27 +0000

Date is 2018-12-29 12:21:21 +0000

Any ideas on how to turn this all into the correct function would be greatly appreciated!!

Upvotes: 2

Views: 553

Answers (2)

user9599273
user9599273

Reputation:

Thank you for all of your help. I have it all working now. My final code is: 

let appDelegate = UIApplication.shared.delegate as! AppDelegate

        let context = appDelegate.persistentContainer.viewContext

        var calendar = Calendar.current
        calendar.timeZone = NSTimeZone.local

        let dateFrom = calendar.startOfDay(for: Date())
        let dateTo = calendar.date(byAdding: .day, value: 1, to: dateFrom)

        let fromPredicate = NSPredicate(format: "timestamp >= %@", dateFrom as NSDate)
        let toPredicate = NSPredicate(format: "timestamp < %@", dateTo! as NSDate)
        let waterPredicate = NSPredicate(format: "drinkWater = %@", "1")

        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Drink")
        request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [waterPredicate, fromPredicate, toPredicate])

        do {
            let result = try context.fetch(request)
            for data in result as! [NSManagedObject] {
                print(data.value(forKey: "timestamp") as! Date)

              drinkMoreButton.setBackgroundImage(UIImage(named: "watericonselected.png"), for: UIControlState.normal)
            }

        } catch {

            print("Failed")
        }

Upvotes: 0

Joakim Danielson
Joakim Danielson

Reputation: 51971

You need to use a date range from start of day to end of day (midnight to midnight) in a compound predicate. Here is a solution based on a similar SO question

var calendar = Calendar.current
calendar.timeZone = NSTimeZone.local

let dateFrom = calendar.startOfDay(for: Date())
let dateTo = calendar.date(byAdding: .day, value: 1, to: dateFrom)

let fromPredicate = NSPredicate(format: "timestamp >= %@", dateFrom as NSDate)
let toPredicate = NSPredicate(format: "timestamp < %@", dateTo! as NSDate)
let waterPredicate = NSPredicate(format: "drinkWater = %@", "1")

let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Drink")
request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [waterPredicate, fromPredicate, toPredicate])

Upvotes: 1

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