ios - Calculate the color at a given point on a gradient between two colors? -

so method write (in objective-c/cocoa, using uicolors, i'm interested in underlying math):

+ (uicolor *)colorbetweencolor:(uicolor *)startcolor andcolor:(uicolor *)endcolor atlocation:(cgfloat)location; 

so example, have 2 colors, pure red , pure blue. given linear gradient between two, want calculate color that's at, say, 33% mark on gradient:
if call method so:

uicolor *resultingcolor = [uicolor colorbetweencolor:[uicolor redcolor] andcolor:[uicolor bluecolor] atlocation:0.33f]; 

i resulting color @ 'b', , similarly, passing 0.0f location return color 'a', , 1.0f return color 'c'.

so question is, how go mixing rgb values of 2 colors , determining color @ 'location' between them?

you linearly interpolate red, green, , blue channels this:

double resultred = color1.red + percent * (color2.red - color1.red); double resultgreen = color1.green + percent * (color2.green - color1.green); double resultblue = color1.blue + percent * (color2.blue - color1.blue); 

where percent value between 0 , 1 (location in first method prototype).