How do I fetch a date range of a week to extract from core data?

Question

How do I query a date range in Swift code data IOS? If I store attributes: date, breakfast meals, lunch meals. How can I query what meals I ate this week?

Answer 1

I was able to get the current week using the following code:

var today = Date()

//finds date for Sunday start of week

var todayweekdaycomp = Calendar.component(.weekday, from: Date())
let startOfWeekSunday = Calendar.current.date(byAdding: .day, value: -(todayweekdaycomp - 1), to: today)!

//finds date for Saturday end of week

let endOfWeekSatvalue = 7 - todayweekdaycomp
let endofWeekSat = Calendar.current.date(byAdding: .day, value: endOfWeekSatvalue, to: today)!


//array of dates this week

var arr: [Date] = []

for n in 1...7 {
    arr.append(Calendar.current.date(byAdding: .day, value: n, to: startOfWeekSunday)!)
}

Answer 2

Defining the begin date :

First you have to define a begin date. This will help us retrieve all the meals from that date .

If you want to get it from 7 days ago define it like that :

let calendar = Calendar.current

let beginDate = calendar.date(byAdding: .day, value: -7, to: Date())!

If you want to get it since the beginning of the week you first need to add this extension :

 extension Date {
    func startOfWeek(using calendar: Calendar = Calendar(identifier: .gregorian)) -> Date {
        calendar.dateComponents([.calendar, .yearForWeekOfYear, .weekOfYear], from: self).date!
    }
}

Then you can define your begin date like so :

let beginDate = Date().startOfWeek()

Creating the request :

// Creating the predicate. 
let predicate = NSPredicate(format: "%K >= %@", #keyPath(YourData.date) ,beginDate as NSDate)
let request: NSFetchRequest<YourData> = YourData.fetchRequest()
// Adding a predicate to your request.   
request.predicate = predicate

Note that you need to replace "YourData" by the name of the class of your meal data object. Once you have your request ready you can fetch it as usual.