CODEWITHSUNDEEP
iosswiftparse-platformnsdate
user1247867
user1247867

Reputation:

To query yesterday records from the Parse table using Swift

I'm going to develop the piece of code to query all the records created yesterday. Well I know it's something very trial. Nevertheless it's one million question for me right now because I'm novice in programming. Below the SWIFT code that doesn't work properly though. For backend I use Parse.com.

var yesterday = NSDate() - 1.day.ago // 1.day.ago isn't valid but what I need.

var query = PFQuery(className:"score") // table name is score
query.whereKey("createdAt", equalTo:"yesterday")

Help please! As always sooner you help higher your chances to win the Tesla Model S Lottery! :)

Upvotes: 0

Views: 1944

Answers (4)

Leo Dabus
Leo Dabus

Reputation: 236370

import UIKit
extension NSDate {
    func xDays(x:Int) -> NSDate {
        return NSCalendar.currentCalendar().dateByAddingUnit(.Day, value: x, toDate: self, options: [])!
    }
}

let today              = NSDate()
let yesterday          = NSDate().xDays(-1)
let dayBeforeYesterday = NSDate().xDays(-2)

Upvotes: 1

BB_Dev
BB_Dev

Reputation: 511

Simply try below code. It works fine in iOS7 and iOS8

let today = NSDate()
let tomorrow = today.dateByAddingTimeInterval(24 * 60 * 60)
let yesterday = today.dateByAddingTimeInterval(-24 * 60 * 60)

Upvotes: 0

Lyndsey Scott
Lyndsey Scott

Reputation: 37300

You can use a pretty cool new attribute of NSCalendar called dateByAddingUnit to easily get yesterday's date:

let today = NSDate()
let yesterday = NSCalendar.currentCalendar().dateByAddingUnit(.CalendarUnitDay,
                                                              value: -1,
                                                              toDate: today,
                                                              options: NSCalendarOptions(0))

Where you set .CalendarUnitDay as the calendar unit you wish to add/subtract by and the value of -1 to indicate the change you want for that calendar unit.

But the problem with your query is that it specifically requests that a PFObject's "createdAt" date equals a specific time, not that the PFObject was created at anytime during that day. So I suggest you create two constraints in your query -- a greater than and a less than between midnight (the start of the day) yesterday and midnight (the start of the day) today so that the query will return all the results in between.

Update:

To get the start of yesterday and today, i.e. midnight, (converted to GMT to match the dates in the parse database, though that line can be removed if that's not your intent) here's what you can do:

var today = NSDate()
let calendar = NSCalendar.autoupdatingCurrentCalendar()
calendar.timeZone = NSTimeZone(forSecondsFromGMT: 0)

let preservedComponents = NSCalendarUnit.YearCalendarUnit | NSCalendarUnit.MonthCalendarUnit | NSCalendarUnit.DayCalendarUnit
today = calendar.dateFromComponents(calendar.components(preservedComponents, fromDate: today))!
var yesterday = NSCalendar.currentCalendar().dateByAddingUnit(.CalendarUnitDay, value: -1, toDate: today, options: NSCalendarOptions(0))

Then to perform your query:

var query = PFQuery(className:"score") // table name is score
query.whereKey("createdAt", greaterThanOrEqualTo: yesterday)
query.whereKey("createdAt", lessThan: today)

Upvotes: 3

Oleg Shulakov
Oleg Shulakov

Reputation: 916

Try this:

var yesterday = NSDate.date() - 1.days

var query = PFQuery(className:"score") // table name is score
query.whereKey("createdAt", equalTo:yesterday)

Pay attention at equalTo:yesterday without quotes

Upvotes: 0

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