检测首次推出的iOS应用 [英] Detect first launch of iOS app

问题描述

我试图在Swift中找到一种方法来检测第一次启动。

I am trying to find a way in Swift to detect the first launch.

推荐答案

通常你会写一个值给NSUserDefaults表示应用程序之前已启动。

Typically you would write a value to NSUserDefaults to indicate that an app has launched before.

let launchedBefore = NSUserDefaults.standardUserDefaults().boolForKey("launchedBefore")
if launchedBefore  {
    print("Not first launch.")
}
else {
    print("First launch, setting NSUserDefault.")
    NSUserDefaults.standardUserDefaults().setBool(true, forKey: "launchedBefore")
}

UPDATE - Swift 3

let launchedBefore = UserDefaults.standard.bool(forKey: "launchedBefore")
if launchedBefore  {
    print("Not first launch.")
} else {
    print("First launch, setting UserDefault.")
    UserDefaults.standard.set(true, forKey: "launchedBefore")
}

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