macosnspredicateeditor

Best way to filter a day with NSPredicateEditor


Did anyone come around a solution for filtering data ( CoreData ) by a day, using NSPredicateEditor ? The idea is to make it most convenient to the user. The standard solution would be to define 2 criteria for date :

  1. one for >= start of the day
  2. another one for <= end of the day.

One EditorRowTemplate should simply look like:

enter image description here

Then, the app should convert the predicate to somewhat like:

"aDate >= '3.5.20210 00:00:00' AND aDate <= '3.5.20210 23:59:59'".

Of course, it should take the value from the date which the user has entered in the row template.

I thought, closures can be a way. So to say, creating the NSPredicate programmatically. But how to use it in NSExpression and grabbing the date from the input ?

The desired row template should look like this :

enter image description here


Solution

  • The row template can convert the predicate in predicate(withSubpredicates:), no other overrides required. In IB the right expressions are Dates.

    override func predicate(withSubpredicates subpredicates: [NSPredicate]?) -> NSPredicate {
        // call super to get the predicate, for example aDate == '3.5.20210 14:03:53'
        let predicate = super.predicate(withSubpredicates: subpredicates)
        // convert the predicate to aDate >= '3.5.2021 00:00:00' AND aDate < '4.5.2021 00:00:00'
        var newPredicate = predicate
        if let comparisonPredicate = predicate as? NSComparisonPredicate,
            let predicateDate = comparisonPredicate.rightExpression.constantValue as? Date {
            let keyPath = comparisonPredicate.leftExpression.keyPath
            var components = Calendar.current.dateComponents([.year, .month, .day], from: predicateDate)
            components.hour = 0
            components.minute = 0
            components.second = 0
            components.calendar = NSCalendar.current
            switch comparisonPredicate.predicateOperatorType {
                case .lessThan:
                    // aDate < '3.5.2021 00:00:00'
                    let date = components.date! as NSDate
                    newPredicate = NSPredicate(format: "%K < %@", keyPath,date)
                case .lessThanOrEqualTo:
                    // aDate < '4.5.2021 00:00:00'
                    components.day = components.day! + 1
                    let date = components.date! as NSDate
                    newPredicate = NSPredicate(format: "%K < %@", keyPath,date)
                case .greaterThan:
                    // aDate >= '4.5.2021 00:00:00'
                    components.day = components.day! + 1
                    let date = components.date! as NSDate
                    newPredicate = NSPredicate(format: "%K >= %@", keyPath,date)
                case .greaterThanOrEqualTo:
                    // aDate >= '3.5.2021 00:00:00'
                    let date = components.date! as NSDate
                    newPredicate = NSPredicate(format: "%K >= %@", keyPath,date)
                case .equalTo:
                    // aDate >= '3.5.2021 00:00:00' AND aDate < '4.5.2021 00:00:00'
                    let startDate = components.date! as NSDate
                    components.day = components.day! + 1
                    let endDate = components.date! as NSDate
                    newPredicate = NSPredicate(format: "%K >= %@ AND %K < %@", keyPath, startDate, keyPath, endDate)
                case .notEqualTo:
                    // NOT (aDate >= '3.5.2021 00:00:00' AND aDate < '4.5.2021 00:00:00')
                    let startDate = components.date! as NSDate
                    components.day = components.day! + 1
                    let endDate = components.date! as NSDate
                    newPredicate = NSPredicate(format: "NOT (%K >= %@ AND %K < %@)", keyPath, startDate, keyPath, endDate)
                default:
                    newPredicate = predicate
            }
        }
        return newPredicate
    }