swift - 调用最近的 PFObject

Question

我有一个计时器，可以将当前日期倒计时到我在 Parse 中设置的日期(类名:“Date”)。现在，它使用我设置的 ObjectId 检索该数据。我想将其设置为使用“updatedAt”列中的日期来调用类中最近更新的对象。我怎样才能做到这一点？

    super.viewDidLoad()

    //      Retrieve the date in Parse

    var query = PFQuery(className:"Date")
        query.getObjectInBackgroundWithId("CSJFqvJDqs") {
            (dateFromParse: PFObject?, error: NSError?) -> Void in
            if error == nil && dateFromParse != nil {
                // Process everything here

                // Step 1: Get the current date.
                let currentDate = NSDate()

                // Step 2: Convert the dateFromParse PFObject into a NSDate object
                let electionDateComponents = NSDateComponents()
                electionDateComponents.day = dateFromParse!["Day"] as! Int
                electionDateComponents.month = dateFromParse!["Month"] as! Int
                electionDateComponents.year = dateFromParse!["Year"] as! Int
                let electionDate = NSCalendar.currentCalendar().dateFromComponents(electionDateComponents)!

                // Step 3: Find the difference between dateFromParse and currentDate
                let timeToElection = electionDate.timeIntervalSinceDate(currentDate)
                let daysToElection = (((timeToElection/60)/60)/24)
                print(daysToElection)

                //              Step 4: Display the number of days of difference on countDown.text
                let daysText =  String(format: "%.0f days", floor(daysToElection))
                self.countDown.text = daysText
            } else {
                print(error)
            }
        }
    }

Answer 1

您应该浏览 SDK 文档和指南:

https://parse.com/docs/ios/api/

https://parse.com/docs/ios/guide#queries

查询具有排序方法。你想做一些类似于

的事情

[query sortDescending:@"updatedAt"];
[query getFirstObjectInBackgroundWithBlock:^(PFObject *dateObject, NSError *error)
{
    //do your stuff
}];

抱歉，刚刚意识到我给了你 obj-c 语法，而你正在使用 swift。我对swift不太熟悉，但是方法应该是一样的。只需称它们为 Swift 风格即可。