如何使用NSRunLoop在objective-C？ [英] how to use NSRunLoop in objective-C?

问题描述

如何使用如何在objective-C中使用NSRunLoop并等待一些变量更改值？

how to use how to use NSRunLoop in objective-C and wait for some variable to change value ?

感谢

推荐答案

我们通常不会在生产中使用NSRunLoop等待变量更改。可以使用回调。

We would not normally use a NSRunLoop in production to wait for a variable to change. One could use a callback.

但是，在单元测试代码中，我们有以下内容：

However, in unit test code we do have the following:

NSDate *twoSecondsFromNow = [NSDate dateWithTimeIntervalSinceNow:2.0];
    while (!callBackInvoked && !errorHasOccured && runCount-- &&  [[NSRunLoop currentRunLoop]  runMode:NSDefaultRunLoopMode beforeDate:twoSecondsFromNow]) {
        twoSecondsFromNow = [NSDate dateWithTimeIntervalSinceNow:2.0];
    }

代码会等待，直到我们的回调被调用，错误发生，的2秒期间，我们等待已经发生。

The code waits until either our callback is invoked, an error occured or the number of 2 second periods we've waited for has occurred. We use this to test delegates that make callbacks.

正如我所说的，我不会在生产代码中这样做。

As I said I would not do this in production code.

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