Question

我是swift的初学者。

在homeviewController中，我声明了一个标签

    @IBOutlet weak var text: UILabel!

如何从安装该应用之日起每周将此数字从0更新为1？

Answer 1

首先，将启动日期存储在应用首次启动的某个位置，例如NSUserDefaults：NSUserDefaults.standardUserDefaults().setObject(NSDate(), forKey: "installDate")。然后，只要您需要显示标签，只需找到当前时间与存储时间之间的差异：

let installDate = NSUserDefaults.standardUserDefaults().objectForKey("installDate") as NSDate!
let today = NSDate()
let calendar = NSCalendar.currentCalendar()
let unitFlags = NSCalendarUnit.WeekOfYear
let dateComponents = calendar.components(unitFlags, fromDate:installDate,  toDate:today, options: NSCalendarOptions.MatchNextTime)
let weeks = dateComponents.weekOfYear

Answer 2

使用NSUserDefaults跟踪您更新text

的日期

NSUserDefaults.standardUserDefaults().setObject(NSDate(), forKey: "lastUpdate")

然后在方法shouldUpdateTheLabel中：

func shouldUpdateLabel() {
    let lastUpdatedSetting = NSUserDefaults.standardUserDefaults().objectForKey("lastUpdate") as? NSDate

    var shouldUpdate = true
    if let lastUpdated = lastUpdatedSetting where NSDate().timeIntervalSinceDate(lastUpdated) < 7 * 24 * 60 * 60 {
            shouldUpdate = false
    }

    if shouldUpdate {
       text.text = "someTextYouWant"
       //Update your label here
       NSUserDefaults.standardUserDefaults().setObject(NSDate(), forKey: "lastUpdate")
      //Record the date you update your label
    }else {
        return
    }

}

每周快速更新文本标签

2 个答案: