Calculate Distance Formula while using a Scale - ios

Question

I am trying to calculate a distance based upon the scale my users draws in.
My user can snap to other points in the game by drawing a line on a grid.
The grid is a numerical value that they can select 8, 16, 24, or 32.
The scale can be changed by the user selecting a whole number (1-10) and fraction number (0, 0.5, 0.75, or 0.125).
The user can select between showing the distance in Metric or Empirical units.
I am having difficulty spitting out the distance once the scale is changed.
Can anyone tell me where I have gone wrong in my math?
- (double) distanceFormula : (float) x1 : (float) y1 : (float) x2 : (float) y2 {
// 1 meter * 3.280839895 feet => feet
// 1 foot * 1 meter/3.280839895 feet => meter
/* Use Pythagora's theorem to calculate distance */
double dx = (x2-x1);
double dy = (y2-y1);
double dist = sqrt(dx*dx + dy*dy);
NSLog(#"Raw Distance %f", dist) ;
return dist;
}
- (NSString *) returnDistanceAsString : (double) distance {
NSString * string;
double d = distance / [self returnGridSize];
double scale = [self returnScaleWhole] + [self returnScaleSub];
if ([self returnUseMetric]) {
//METRIC
int tempCentim = (d * kCMConst) / 2;
if (tempCentim < 1) {
string = [NSString stringWithFormat:#"%d mm", tempCentim];
} else if (tempCentim > 1) {
string = [NSString stringWithFormat:#"%d mm", tempCentim];
} else if (tempCentim > 100) {
//eventually going to add cm mm
}
} else {
//EMPERICAL
int RL = d * scale;
int feet = RL / 12.0;
int inches = (int)RL % 12;
string = [NSString stringWithFormat:#"%i' %i\"", feet, inches];
}
return string;
}

Answer 1

The main questionable thing I noticed is that, in metric, you're neglecting to multiply by scale, but you are multiplying by kCMConst/2. You don't explain what kCMConst is, but it seems unlikely to be a value that needs to be divided by 2.