NSTimer可靠的替代品 [英] NSTimer Reliable Alternatives

问题描述

我有一个应用程序应该每1秒记录一些事情，我现在正在使用 NSTimer ，但如果我的应用程序转换屏幕（或几乎其他任何东西，真的）它会使计时器变慢而导致读数不准确。

I have an application that is supposed to log certain things every 1 second and I'm currently using NSTimer, but if my application transitions screens (or almost anything else, really) it slows down the timer a little bit making for inaccurate readings.

什么是可靠的替代品？我当前的代码如下：

What is a reliable alternative to use? My current code is as follows:

timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(update) userInfo:nil repeats:YES];

推荐答案

NSTimer无法保证按时准时发射。但是你可以以比现在更可靠的方式使用NSTimer。当您使用 scheduledTimerWithTimeInterval 时，您将创建一个NSTimer，它在 NSDefaultRunLoopMode 的运行循环中进行调度。在使用UI时，此模式暂停，因此在有用户交互时，您的计时器不会触发。要避免此暂停，请使用模式 NSRunLoopCommonModes 。要做到这一点，你必须自己安排计时器：

NSTimer is not guaranteed to fire exactly on time, ever. But you can use an NSTimer in a much more reliable way than you are now. When you use scheduledTimerWithTimeInterval you create an NSTimer which is scheduled in the run loop for NSDefaultRunLoopMode. This mode is paused when the UI is being used, so your timers won't fire when there is user interaction. To avoid this pause use the mode NSRunLoopCommonModes. To do this you will have to schedule the timer yourself like so:

timer = [NSTimer timerWithTimeInterval:1 target:self selector:@selector(update) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];

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