Question

How can I make a method that takes in a float from 0-50, and gives out a green color with uniform intensity?

So if the input value is 0, the color is black:

[UIColor colorWithRed:0 green:0 blue:0];

and if the input value is 50, the color is the max green color:

[UIColor colorWithRed:0 green:255.0/255.0 blue:0];

And so if the input factor is somewhere in the middle, then the color should be somewhere in the middle. So going from 0-50, it should go from the darkest green to the lightest green. Should be simple but I’m not sure what I’m missing:

//factor is a float from 0-50
UIColor *greenColor = [UIColor colorWithRed:0 green:factor/255.0 blue:0 alpha:1.0];

This code generates a green color, but doesn’t fluctuate much, so you only see about one shade of green.

Answer 1

You need to scale the RGB max value (255) against your own max value (50). And all you need is fairly simple math:

colorVal = 255 * x / 50

where x is the intesity on the scale from 0 to 50. So:

255 * 0  / 50 = 0 
255 * 50 / 50 = 255
255 * 25 / 50 = 128 (rounded up from 127.5)