首次安装应用程序时存储变量 [英] Storing a variable when the app is first installed

问题描述

首次安装应用时尝试存储变量 DateInstalled ，但每次应用加载此变量时，新日期都会覆盖此变量。

Attempting to store the variable DateInstalled when the app is first installed, but each time the app loads this variable is overridden by the new date.

我是 Xcode 的新手，所以答案可能很明显。我发现下面的代码将变量存储在用户默认值中，但每次它似乎跳到else语句。

I am new to Xcode so the answer is probably obvious. I found this code below to store the variable in the user defaults but every time it seems to skip to the else statement.

var DateInstalled: NSDate {
    get {
        if let returnValue = NSUserDefaults.standardUserDefaults().objectForKey("DateInstalled") as? NSDate {     
            return returnValue
        } else {
            NSLog("Saving new Date")
            return NSDate()          // Default value
        }
    }
    set {
        NSUserDefaults.standardUserDefaults().setObject(newValue, forKey: "DateInstalled")
        NSUserDefaults.standardUserDefaults().synchronize()
    }
}

推荐答案

嘿@Curtis Cowan试试这个

Hey @Curtis Cowan try with this

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

            let firstLaunch = NSUserDefaults.standardUserDefaults().boolForKey("FirstLaunchTime")
            if firstLaunch  {
               println("Not First launch")
            }
            else {
                println("First launch")
                NSUserDefaults.standardUserDefaults().setObject(NSDate(), forKey:"FirstLaunchTime")
                 }

            return true
      }

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