用于Objective-C的计时器输出

Question

This question is a branch off of my previous question from earlier today, but is still a new question. I'm having issues with a timer loop that I declared in the .m file:

// battery level connection timer
- (void)batteryLevelTimerRun
{
    batteryLevelSecondsCount = batteryLevelSecondsCount - 1;
    int batteryLevelProgress = batteryLevelSecondsCount;

    NSString *timerOutput = [NSString stringWithFormat:@"Battery Level: %d%%", batteryLevelProgress];
    batteryLevelLabel.text = timerOutput;

    float batteryLevelProgressFloat = batteryLevelSecondsCount / 100;
    [batteryLevel setProgress:batteryLevelProgressFloat animated:YES];

    if (batteryLevelSecondsCount == 20)
    {
        batteryLevelLabel.textColor = [UIColor orangeColor];
    }
    else if (batteryLevelSecondsCount == 10)
    {
        batteryLevelLabel.textColor = [UIColor redColor];
    }
    else if (batteryLevelSecondsCount == 0)
    {
        [batteryLevelTimer invalidate];
        batteryLevelTimer = nil;
    }
}

// battery level connection timer
- (void)batteryLevelSetTimer
{
    batteryLevelSecondsCount = 100;
    batteryLevelTimer = [NSTimer scheduledTimerWithTimeInterval:9.0 target:self selector:@selector(batteryLevelTimerRun) userInfo:nil repeats:YES];
}

In the .h file, I declared:

@interface MonitoringViewController : UIViewController

{
       IBOutlet UILabel *batteryLevelLabel; 
       IBOutlet UIProgressView *batteryLevel;

       NSTimer *batteryLevelTimer;
       int batteryLevelSecondsCount;
}

I assigned [self batteryLevelTimer] to a button press. When I ran the code, I got an odd response in the batteryLevelLabel UILabel field. It said Battery Level: -1% . Any idea why this would be? I also setup the UIProgressView to decrement along with label, and that is also dysfunctional (was set to 0), probably because it thinks that the value it was given was -1 so that it defaulted to 0 (UIProgressView value goes from 0.0 to 1.0). Is there some mathematical/logic error I'm missing out on here?

Answer 1

Your code seems ok and works just fine in my test project (I connected button to batteryLevelSetTimer and label counted down to zero as expected). Except for progress bar part -- you should change the line:

float batteryLevelProgressFloat = batteryLevelSecondsCount / 100;

to

float batteryLevelProgressFloat = batteryLevelSecondsCount / 100.0;

because both batteryLevelSecondsCount and 100 are integers, and integer division always yields integer result, which varies between 0 and 1 in your case.