How to add milliseconds to a stopwatch app? - ios

Question

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!

Answer 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.