iOS - 无法将NSDate存储到NSUserDefaults中 [英] iOS - Not able to store NSDate into NSUserDefaults

问题描述

在我的应用程序中，我想首次存储应用程序启动的日期。

我在应用程序中使用以下代码：didFinishLaunchingWithOptions方法

In my application, i want to store the date at which the app is started for the first time.
I'm using following code in application:didFinishLaunchingWithOptions method

NSDate* today = [NSDate date];
[[NSUserDefaults standardUserDefaults] registerDefaults: @{@"CONSCIENCE_START_DATE" : today}];

NSLog(@"%@", [[NSUserDefaults standardUserDefaults] objectForKey:@"CONSCIENCE_START_DATE"]);

但每次启动应用程序时，都会打印应用程序启动的时间。它没有打印我启动应用程序的日期。

But every time when i start the application, its printing the time at which the app is starting. Its not printing the date at which i started the app.

我试图重置模拟器并再次运行代码。仍然没有成功。有人可以指出我的代码中的错误吗？

I tried to reset the simulator and ran the code again. Still no success. Can some one point me the error in my code please?

推荐答案

因为你的目标是第一次跟踪用户启动你的应用程序，在应用程序中你需要这样的东西：didFinishLaunchingWithOptions ：

Since your goal to is keep track of the very first time a user starts your app, you need something like this in application:didFinishLaunchingWithOptions:

NSDate *date = [[NSUserDefaults standardUserDefaults] objectForKey:@"CONSCIENCE_START_DATE"];
if (!date) {
    // This is the 1st run of the app
    date = [NSDate date];
    [[NSUserDefaults standardUserDefaults] setObject:date forKey:@"CONSCIENCE_START_DATE"]; // Save date
}

NSLog(@"First run was %@", date);

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