在指定时间段iPhone后清除NSUserDefaults [英] Clearing NSUserDefaults after specified time period iPhone

问题描述

我已经创建了NSUserDefaults对象，每当偶数发生时，它将被更新为新值。
我想要的是（根据我的应用程序要求）该对象应该每7天清除一次。
像第一次NSUserDefaults今天更新，所以7天后，一个方法应该工作，并清除NSUserDefaults。

I have created NSUserDefaults object, it will be updated with the new value whenever an even will occur. What I want is (as per my application requirement) that object should be cleared every 7 days. Like if 1st time that NSUserDefaults are updated today so exact after 7 days, a method should work and clear the NSUserDefaults. So that, new values would be assigned from then on for the next 7 days.

推荐答案

你可以做的是存储一个NSDate对象。然后每次启动应用程序（或更频繁地）检查当时和现在之间的时间差是否为7天。

What you can do is store an NSDate object. Then every time the application is launched (or more often) check if the time difference between then and now is 7 days.

const NSString *kFirstLaunchDateKey = @"firstLaunchDate";
NSDate *firstLaunchDate = [[NSUserDefaults standardUserDefaults] objectForKey:kFirstLaunchDateKey];

//  If this is the first time the app has been launched we record right now as the first time the app was launched.
if (!firstLaunchDate) {
    [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:kFirstLaunchDateKey];
    return;
}

NSTimeInterval *diff = abs([firstLaunchDate timeIntervalSinceNow]);
if (diff > 60 * 60 * 24 * 7) {
//      Seven days have passed since the app was first launched. 
//      Display the rate button.
}

如果是

- (void)removePersistentDomainForName:(NSString *)domainName

以您的应用程序包标识符作为参数。

With your application’s bundle identifier as the parameter.

从Apple的文档：

domainName
需要其键和值的域。此值应等于应用程序的包标识符。

domainName The domain whose keys and values you want. This value should be equal to your application's bundle identifier.

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