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copied!<pre><code>static void RGBtoHSV( float r, float g, float b, float *h, float *s, float *v ) { float min, max, delta; min = MIN( r, MIN( g, b )); max = MAX( r, MAX( g, b )); *v = max; // v delta = max - min; if( max != 0 ) *s = delta / max; // s else { // r = g = b = 0 // s = 0, v is undefined *s = 0; *h = -1; return; } if( r == max ) *h = ( g - b ) / delta; // between yellow & magenta else if( g == max ) *h = 2 + ( b - r ) / delta; // between cyan & yellow else *h = 4 + ( r - g ) / delta; // between magenta & cyan *h *= 60; // degrees if( *h < 0 ) *h += 360; } static void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v ) { int i; float f, p, q, t; if( s == 0 ) { // achromatic (grey) *r = *g = *b = v; return; } h /= 60; // sector 0 to 5 i = floor( h ); f = h - i; // factorial part of h p = v * ( 1 - s ); q = v * ( 1 - s * f ); t = v * ( 1 - s * ( 1 - f ) ); switch( i ) { case 0: *r = v; *g = t; *b = p; break; case 1: *r = q; *g = v; *b = p; break; case 2: *r = p; *g = v; *b = t; break; case 3: *r = p; *g = q; *b = v; break; case 4: *r = t; *g = p; *b = v; break; default: // case 5: *r = v; *g = p; *b = q; break; } } ... CGFloat r, g, b, a, h, s, v; const CGFloat *comp = CGColorGetComponents([myUIColor CGColor]); r = comp[0]; g = comp[1]; b = comp[2]; a = comp[3]; RGBtoHSV(r, g, b, &h, &s, &v); </code></pre> <p>The code above assumes the UIColor is setup in the RGB space (which is typical). If the color is in another color space it will crash and / or have undefined behavior.</p> <p>iOS 5.0 has <code>- (BOOL)getHue:(CGFloat *)hue saturation:(CGFloat *)saturation brightness:(CGFloat *)brightness alpha:(CGFloat *)alpha</code> which does all this work for you. But it's not available yet.</p>

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