Sorting Firebase Realtime Database data in Swift

Question

enter image description here

I need to show these data in a table view, but they have been on the table view in mixing order. How can I put them in the same order as in the database. Please help, I will deeply appreciated.

First image shows my iPhone screen after running the project, second one is the database. I want them exact order as in the database.

Not clear how your data is sorted in Firebase DB — is it by key/UID or by priority? — Paulo Mattos
– Paulo Mattos, Commented Apr 13, 2017 at 1:46
Thank you for response, I have added the 2nd image to be more clear. — muh comen
– muh comen, Commented Apr 13, 2017 at 1:56
@muhcomen check my answer. If you have another questions - you are welcome — Vlad Pulichev
– Vlad Pulichev, Commented Apr 13, 2017 at 5:43
Are you sure you want them displayed in the table in the same order shown in the screenshot? That's NOT the order it appears you wrote them to the database. i.e. period0, period1, period2 appears to be the order you wrote them, not period0, period1, period10... The period10 is coming after period1 because they are sorted via ASCII sorting and showing in ASCII order, not the order you wrote them. If that's the case then the accepted answer won't work. — Jay
– Jay, Commented Apr 14, 2017 at 17:26

Vlad Pulichev · Accepted Answer · 2017-04-13 06:33:31Z

2

I hope periods objects look like this:

struct PeriodItem {
    let key: String

    let periodEnd: String
    let periodName: String
    let periodStart: String

    let ref: FIRDatabaseReference?

    init(periodEnd: String, periodName: String, periodStart: String, key: String = "") {
        self.key = key

        self.periodEnd = periodEnd
        self.periodName = periodName
        self.periodStart = periodStart

        self.ref = nil
    }

    init(snapshot: FIRDataSnapshot) {
        key = snapshot.key

        let snapshotValue = snapshot.value as! [String: AnyObject]
        periodEnd = snapshotValue["periodEnd"] as! String
        periodName = snapshotValue["periodName"] as! String
        periodStart = snapshotValue["periodStart"] as! String

        ref = snapshot.ref
    }

    func toAnyObject() -> Any {
        return [
            "periodEnd": periodEnd,
            "periodName": periodName,
            "periodStart": periodStart,

            "key": key
        ]
    }
}

So

When you fill your array of Periods fully, just use sorting:

// periods - array of objects from firebase database
let yourTableViewPeriodsArray = periods.sorted(by: { $0.key < $1.key }) // maybe ">" instead of "<"

Then:

DispatchQueue.main.async {
    self.tableView.reloadData()
}

Hope it helps.

edited Apr 13, 2017 at 6:33

answered Apr 13, 2017 at 5:42

Vlad Pulichev

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1 Comment

Will Mays Over a year ago

When I call print([PeriodItem].self) in viewDidLoad I get Array<PeriodItem> instead of the actual array. Any ideas?

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