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从现在起测量时间间隔

发布于 2024-11-09 23:21:08 字数 206 浏览 0 评论 0原文

任何人都知道或可以提供一些与“timeIntervalSinceNow”方法相关的示例代码...

我需要类似... time2（当应用程序进入前台时） - time1（当应用程序进入后台时）= time3（时间差）...这样我就可以使用这个数字（首选以秒为单位）来计算应用程序处于后台时我损失的时间！

我正在尝试创建日期对象、接收对象并在标签中显示/使用......

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爱的故事 2024-11-16 23:21:08

实际上，要回答您原来的问题，myles，您可以使用 timeIntervalSinceNow 。
在下面的语句中，inputDate已初始化为NSDate并设置为某个日期（您可以尝试[NSDate *inputDate = [NSDate date];< /code> 将日期设置为当前日期和时间。

NSTimeInterval timeToAlert =[inputDate timeIntervalSinceNow];

下一行是将 NSTimeInterval 放入字符串中的方法。

NSMutableString *timeinterval = [NSMutableString string];
[timeinterval appendFormat:@"%f",timeToAlert];

最后，应用程序委托类通常可以编写代码来处理。进入和退出后台祝你好运！

Actually, to answer your original question, myles, you can use timeIntervalSinceNow.
In the statement below, inputDate has been initialized as an NSDate and set to some date (you could just try [NSDate *inputDate = [NSDate date]; to set the date at the current date and time.

NSTimeInterval timeToAlert =[inputDate timeIntervalSinceNow];

The next line is a way to put that NSTimeInterval into a string.

NSMutableString *timeinterval = [NSMutableString string];
[timeinterval appendFormat:@"%f",timeToAlert];

Finally, the app delegate class is typically where code can be written to handle coming in and out of background. Good luck!

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ˇ宁静的妩媚 2024-11-16 23:21:08

timeIntervalSinceNow 告诉您 NSDate 与当前时间的偏移量。您需要timeIntervalSinceDate:：

NSDate *appEnteredForeground = ...;
NSDate *appEnteredBackground = ...;

NSTimeInterval difference = [appEnteredBackground timeIntervalSinceDate: appEnteredForeground];

timeIntervalSinceNow tells you the offset of an NSDate from the current time. You want timeIntervalSinceDate::

NSDate *appEnteredForeground = ...;
NSDate *appEnteredBackground = ...;

NSTimeInterval difference = [appEnteredBackground timeIntervalSinceDate: appEnteredForeground];

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夜还是长夜 2024-11-16 23:21:08

您可以使用 timeIntervalSinceDate: 方法计算两个日期之间的差异：

//When app enters background:
self.backgroundDate = [NSDate date]; //this should be a property 
//...
//When the app comes back to the foreground:
NSTimeInterval timeSpentInBackground = [[NSDate date] timeIntervalSinceDate:self.backgroundDate];

NSTimeInterval 只是 double 的 typedef，以秒为单位。 [NSDate date] 使用当前日期和时间实例化一个 NSDate 对象。

You can calculate the difference between two dates with the timeIntervalSinceDate: method:

//When app enters background:
self.backgroundDate = [NSDate date]; //this should be a property 
//...
//When the app comes back to the foreground:
NSTimeInterval timeSpentInBackground = [[NSDate date] timeIntervalSinceDate:self.backgroundDate];

NSTimeInterval is simply a typedef for double, it's measured in seconds. [NSDate date] instantiates an NSDate object with the current date and time.

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