How to add milliseconds to a stopwatch app?

问题

Ok, so I've based my stopwatch app code from this tutorial right here http://iphonedev.tv/blog/2013/7/7/getting-started-part-3-adding-a-stopwatch-with-nstimer-and-our-first-class I like the way it is set up, but I can't figure out how to add hundredths of a second to it, anyone know how to do this?

My ViewController.m file

#import "ViewController.h"
#import "Foundation/Foundation.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (NSTimer *)createTimer
{
     return [NSTimer scheduledTimerWithTimeInterval:0.01
                                        target:self
                                      selector:@selector(timerTicked:)
                                      userInfo:nil
                                       repeats:YES];
}

- (void)timerTicked:(NSTimer *)timer
{
     _currentTimeInSeconds++;

     self.timeLabel.text = [self formattedTime:_currentTimeInSeconds];
}

- (NSString *)formattedTime:(int)totalSeconds
{
    int hundredths = totalSeconds % 60;
    int seconds = totalSeconds % 60;
    int minutes = (totalSeconds / 60) % 60;
    int hours = totalSeconds / 3600;

    return [NSString stringWithFormat:@"%02d:%02d:%02d.%02d", hours, minutes, seconds, hundredths];
}

- (IBAction)startButtonPressed:(id)sender
{
    if (!_currentTimeInSeconds)
    {
        _currentTimeInSeconds = 0 ;
    }

    if (!_theTimer)
    {
        _theTimer = [self createTimer];
    }
}

- (IBAction)stopButtonPressed:(id)sender
{
    [_theTimer invalidate];
}

- (IBAction)resetButtonPressed:(id)sender
{
    if (_theTimer)
    {
        [_theTimer invalidate];
        _theTimer = [self createTimer];
    }

    _currentTimeInSeconds = 0;

    self.timeLabel.text = [self formattedTime:_currentTimeInSeconds];
}

@end

Thanks again for anybody who can help!

回答1:

First, you should change the name of your variable from _currentTimeInSeconds to _currentTimeInHundredths (or something shorter if you want).

Next, you need to update the logic in your - (NSString *)formattedTime:(int)totalSeconds method. Try something like this (changing totalSeconds to totalHundredths for the same reason as before).

int hours = totalHundredths / 360000;
int minutes = (totalHundredths - (hours * 360000)) / 6000;
int seconds = (totalHundredths - (hours * 360000) - (minutes * 6000)) / 100;
int hundredths = totalHundredths - (hours * 360000) - (minutes * 6000) - (seconds * 100);

I haven't tested the math on the numbers, but they should be right.

来源：https://stackoverflow.com/questions/24792042/how-to-add-milliseconds-to-a-stopwatch-app

标签

ios

objective-c

nstimer