const CGFloat *colors = CGColorGetComponents( curView.backgroundColor.CGColor );

These links provide further details:

• UIColor Reference
• CGColorGetComponents reference

const float* colors = CGColorGetComponents( curView.backgroundColor.CGColor );

Thanks. I had to add the const at the start of the line as it was generating a warning.

In iOS 5 you could use:

CGFloat red = 0.0, green = 0.0, blue = 0.0, alpha =0.0;
[multipliedColor getRed:&red green:&green blue:&blue alpha:&alpha];

 UIColor *color = [[UIColor greenColor] retain]; //line 1


//OR(You will have color variable either like line 1 or line 2)


color = curView.backgroundColor;//line 2
CGColorRef colorRef = [color CGColor];


int _countComponents = CGColorGetNumberOfComponents(colorRef);


if (_countComponents == 4) {
const CGFloat *_components = CGColorGetComponents(colorRef);
CGFloat red     = _components[0];
CGFloat green = _components[1];
CGFloat blue   = _components[2];
CGFloat alpha = _components[3];


NSLog(@"%f,%f,%f,%f",red,green,blue,alpha);
}


[color release];

Just made a category for this.

NSLog(@"%f", [UIColor blueColor].blue); // 1.000000

Goes something like:

typedef enum { R, G, B, A } UIColorComponentIndices;


@implementation UIColor (EPPZKit)


-(CGFloat)red
{ return CGColorGetComponents(self.CGColor)[R]; }


-(CGFloat)green
{ return CGColorGetComponents(self.CGColor)[G]; }


-(CGFloat)blue
{ return CGColorGetComponents(self.CGColor)[B]; }


-(CGFloat)alpha
{ return CGColorGetComponents(self.CGColor)[A]; }


@end

Part of eppz!kit with more UIColor goodies.

Hopefully this will be helpful

CGFloat red, green, blue, alpha;


//Create a sample color


UIColor *redColor = [UIColor redColor];


//Call


[redColor getRed: &red
green: &green
blue: &blue
alpha: &alpha];
NSLog(@"red = %f. Green = %f. Blue = %f. Alpha = %f",
red,
green,
blue,
alpha);

I wanted to get the background color of the UITableViewStyle "UITableViewStyleGrouped" so in the viewDidAppear: method I added the code:

NSLog(@"%@", self.tableView.backgroundView.backgroundColor);

It did what I anticipated and returned the log:

UIDeviceRGBColorSpace 0.937255 0.937255 0.956863 1

So in short just type in NSLog(@"%@", [UIColor whateverColor]);

SWIFT 3 & 4

I found that cgColor.components would not always return 4 color values, so I changed this so it gets them from a CIColor wrapper

extension UIColor {
var redValue: CGFloat{ return CIColor(color: self).red }
var greenValue: CGFloat{ return CIColor(color: self).green }
var blueValue: CGFloat{ return CIColor(color: self).blue }
var alphaValue: CGFloat{ return CIColor(color: self).alpha }
}

SWIFT 2

extension UIColor {
var red: CGFloat{ return CGColorGetComponents(self.CGColor)[0] }
var green: CGFloat{ return CGColorGetComponents(self.CGColor)[1] }
var blue: CGFloat{ return CGColorGetComponents(self.CGColor)[2] }
var alpha: CGFloat{ return CGColorGetComponents(self.CGColor)[3] }
}

It's not the most efficient way so I wouldn't go using this where a view will be constantly re-drawn.

Since iOS 2.0 there is a private instance method on UIColor called styleString which returns an RGB or RGBA string representation of the color, even for colors like whiteColor outside the RGB space.

Objective-C:

@interface UIColor (Private)


- (NSString *)styleString;


@end


// ...


[[UIColor whiteColor] styleString]; // rgb(255,255,255)
[[UIColor redColor] styleString]; // rgb(255,0,0)
[[UIColor lightTextColor] styleString]; // rgba(255,255,255,0.600000)

In Swift you could use a bridging header to expose the interface. With pure Swift, you will need to create an @objc protocol with the private method, and unsafeBitCast UIColor with the protocol:

@objc protocol  UIColorPrivate {
func styleString() -> String
}


let white = UIColor.whiteColor()
let red = UIColor.redColor()
let lightTextColor = UIColor.lightTextColor()


let whitePrivate = unsafeBitCast(white, UIColorPrivate.self)
let redPrivate = unsafeBitCast(red, UIColorPrivate.self)
let lightTextColorPrivate = unsafeBitCast(lightTextColor, UIColorPrivate.self)


whitePrivate.styleString() // rgb(255,255,255)
redPrivate.styleString() // rgb(255,0,0)
lightTextColorPrivate.styleString() // rgba(255,255,255,0.600000)

Using HandyUIKit makes this really easy:

import HandyUIKit


let color = UIColor(red: 0.1, green: 0.2, blue: 0.3, alpha: 0.4)


// get any of the rgba values
color.rgba.red    // => 0.1
color.rgba.green  // => 0.2
color.rgba.blue   // => 0.3
color.rgba.alpha  // => 0.4

There is also a similar option to get hsba values:

let color = UIColor(hue: 0.1, saturation: 0.2, brightness: 0.3, alpha: 0.4)


// you can get any of the hsba values, too
color.hsba.hue         // => 0.1
color.hsba.saturation  // => 0.2
color.hsba.brightness  // => 0.3
color.hsba.alpha       // => 0.4

Simply install it using Carthage and you're good to go.

I hope it helps!

Swift 3 version of David Rees answer:

extension UIColor {


var redValue: CGFloat{
return cgColor.components! [0]
}


var greenValue: CGFloat{
return cgColor.components! [1]
}


var blueValue: CGFloat{
return cgColor.components! [2]
}


var alphaValue: CGFloat{
return cgColor.components! [3]
}
}

set your UIColor like this

UIColor.FromRGB(128, 179, 255)

this is for Xamarin ios... but for sure there is a method like this in swift.

Some useful macros I've made for this and other color controls:

In your case you would just use

getRGBA(myColor, red, green, blue, alpha);


NSLog(@"Red Value: %f", red);
NSLog(@"Blue Value: %f", green);
NSLog(@"Green Value: %f", blue);

Macros:

#define rgba(r,g,b,a) [UIColor colorWithRed:((float)(r))/255.0f green:((float)(g))/255.0f blue:((float)(b))/255.0f alpha:a]
#define rgb(r,g,b) rgba(r, g, b, 1.0f)


#define rgbaf(r,g,b,a) [UIColor colorWithRed:(r) green:(g) blue:(b) alpha:a]
#define rgbf(r,g,b) rgbaf(r, g, b, 1.0f)


#define rgba_fromColor(__color, __r, __g, __b, __a) \
CGFloat __r, __g, __b, __a;\
UIColor *__unpackedColor = [NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:__color]];/*Bring system colors into compatible color-space (e.g. DarkGrayColor)*/\
[__unpackedColor getRed:&__r green:&__g blue:&__b alpha:&__a];
#define getRGBA(__color, __r, __g, __b, __a) hsba_fromColor(__color, __r, __g, __b, __a)


#define getRed(__color)  (\
(^float (void){\
rgba_fromColor(__color, r, g, b, a);\
return r;\
})()\
)


#define getGreen(__color)  (\
(^float (void){\
rgba_fromColor(__color, r, g, b, a);\
return g;\
})()\
)


#define getBlue(__color)  (\
(^float (void){\
rgba_fromColor(__color, r, g, b, a);\
return b;\
})()\
)


#define getAlpha(__color)  (\
(^float (void){\
rgba_fromColor(__color, r, g, b, a);\
return a;\
})()\
)




















#define hsba(h,s,b,a) [UIColor colorWithHue:((float)(h))/360.0f saturation:((float)(s))/100.0f brightness:((float)(b))/100.0f alpha:a]
#define hsb(h,s,b) hsba(h, s, b, 1.0f)


#define hsbaf(h,s,b,a) [UIColor colorWithHue:(h) saturation:(s) brightness:(b) alpha:a]
#define hsbf(h,s,b) rgbaf(h, s, b, 1.0f)


#define hsba_fromColor(__color, __h, __s, __b, __a) \
CGFloat __h, __s, __b, __a;\
UIColor *__unpackedColor = [NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:__color]];/*Bring system colors into compatible color-space (e.g. DarkGrayColor)*/\
[__unpackedColor getHue:&__h saturation:&__s brightness:&__b alpha:&__a];
#define getHSBA(__color, __h, __s, __b, __a) rgba_fromColor(__color, __h, __s, __b, __a)


#define getHue(__color)  (\
(^float (void){\
hsba_fromColor(__color, h, s, b, a);\
return h;\
})()\
)


#define getSaturation(__color)  (\
(^float (void){\
hsba_fromColor(__color, h, s, b, a);\
return s;\
})()\
)


#define getBrightness(__color)  (\
(^float (void){\
hsba_fromColor(__color, h, s, b, a);\
return b;\
})()\
)


/*
///already defined in RGBA macros
#define getAlpha(__color)  (\
(^float (void){\
hsba_fromColor(__color, h, s, b, a);\
return a;\
})()\
)
*/

The top voted answer is outdated:

error: :3:1: error: 'CGColorGetComponents' has been replaced by property 'CGColor.components'

Instead, use

myUIColor.cgColor.components

You can use CIColor components (swift 5)

let ciColor = CIColor(color: backgroundColor)
let alpha = ciColor.alpha
let red = ciColor.red
let blue = ciColor.blue
let green = ciColor.green

this works for non-RGB color space too

CGColor's property components is what you need.

The code below

UIColor.separator.cgColor.components

Prints the following

Optional([0.23529411764705882, 0.23529411764705882, 0.2627450980392157, 0.29])

Where the first element of the array is a red value, the second one is a green value, the third one is a blue value and the last one is an alpha value. Pretty simple!