Question

我正在尝试编写一个返回当前位置的方法。当我等待30秒，1分钟或2分钟（在设置中设置）时，我显示警报视图。我允许用户绕过定时器等待，其中alertView按钮接受我将在警报视图中显示和更新的当前准确度。我的代码中有几个漏洞我需要帮助。本质上，它是知道如何让getCurrentLocation方法等待计时器。我不能只是使用延迟，因为我计划在用户点击按钮或满足位置精度时强制计时器到期（这在计时器中检查）。这是代码：

- (void)timerFireMethod {
    static int elapsedTime = 0;
    elapsedTime++;
    if (elapsedTime >= gpsTimeout) {
        [locationManager stopUpdatingLocation];
        elapsedTime = 0; // reset static variable
        // !!! How do I do the following !!!
        //  do something to allow getCurrentLocation to return
    }
    if ((currentLocation.horizontalAccuracy <= gpsDesiredAccuracy) & (currentLocation.verticalAccuracy <= 2*gpsDesiredAccuracy)) {
        [locationManager stopUpdatingLocation];
        elapsedTime = 0; // reset static variable
        //  do something to allow getCurrentLocation to return
    }
}

- (CLLocation *)getCurrentLocation {
    // check if current accuracy is good enough and return if true
    if ((currentLocation.horizontalAccuracy <= gpsDesiredAccuracy) & (currentLocation.verticalAccuracy <= 2*gpsDesiredAccuracy)) {
        [locationManager stopUpdatingLocation];
        return currentLocation;
    } else {
        // show alert with count down timer
        UIAlertView *gpsAlertView = [[UIAlertView alloc] initWithTitle:nil message:@"tbd put in timer and list location accuracy updates" delegate:self cancelButtonTitle:@"Continue With Current Accuracy" otherButtonTitles:nil];
        [gpsAlertView show];
        // start timer
        NSTimer *gpsTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                                         target:self selector:@selector(timerFireMethod:)
                                                       userInfo:nil repeats:YES];

        // !!! How do I do the following !!!
        // wait for when timer expires,
        // the user to press "Continue With Current Accuracy" button (can force timer to expire?)   
        return currentLocation;
    }
}

Answer 1

等待任何计时器或任何加速度计或用户事件的方法是使用return语句将当前方法退回到UI运行循环。

等待之后你想做的任何事情都可以进入计时器或事件回调方法。

如何在返回位置之前等待计时器？

1 个答案: