UIColor category to allow specification of color like [UIColor colorWithRGB24:0xfcfc22];

UIColor+KDJPackedRGB.h

// Copyright (C) 2013 Kristopher Johnson
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#import <UIKit/UIKit.h>

@interface UIColor (KDJPackedRGB)

// Return opaque color with specified 24-bit RGB components.
//
// e.g. [UIColor colorWithRGB24:0xff0000] is red;
//      [UIColor colorWithRGB24:0xffff00] is yellow;
//      [UIColor colorWithRGB24:0x8080c0] is a pale blue

+ (UIColor *)colorWithRGB24:(NSUInteger)rrggbb;


// Return color with specified RGB and alpha hex components.
//
// e.g. [UIColor colorWithRGBA32:0xff0000ff] is pure red;
//      [UIColor colorWithRGBA32:0x8080cc80] is a pale translucent blue

+ (UIColor *)colorWithRGBA32:(NSUInteger)rrggbbaa;


// Return color with specified alpha and RGB hex components.
//
// e.g. [UIColor colorWithARGB32:0xffff0000] is pure red;
//      [UIColor colorWithARGB32:0x808080c0] is a pale translucent blue

+ (UIColor *)colorWithARGB32:(NSUInteger)aarrggbb;

@end

UIColor+KDJPackedRGB.m

// Copyright (C) 2013 Kristopher Johnson
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#import "UIColor+KDJPackedRGB.h"

@implementation UIColor (KDJPackedRGB)

+ (UIColor *)colorWithRGB24:(NSUInteger)rrggbb {
    NSUInteger redComponent   = (rrggbb & 0x00ff0000) >> 16;
    NSUInteger greenComponent = (rrggbb & 0x0000ff00) >> 8;
    NSUInteger blueComponent  = (rrggbb & 0x000000ff);

    return [UIColor colorWithRed:(redComponent/255.0)
                           green:(greenComponent/255.0)
                            blue:(blueComponent/255.0)
                           alpha:1.0];
}

+ (UIColor *)colorWithRGBA32:(NSUInteger)rrggbbaa {
    NSUInteger redComponent   = (rrggbbaa & 0xff000000) >> 24;
    NSUInteger greenComponent = (rrggbbaa & 0x00ff0000) >> 16;
    NSUInteger blueComponent  = (rrggbbaa & 0x0000ff00) >> 8;
    NSUInteger alphaComponent = (rrggbbaa & 0x000000ff);

    return [UIColor colorWithRed:(redComponent/255.0)
                           green:(greenComponent/255.0)
                            blue:(blueComponent/255.0)
                           alpha:(alphaComponent/255.0)];
}

+ (UIColor *)colorWithARGB32:(NSUInteger)aarrggbb {
    NSUInteger alphaComponent = (aarrggbb & 0xff000000) >> 24;
    NSUInteger redComponent   = (aarrggbb & 0x00ff0000) >> 16;
    NSUInteger greenComponent = (aarrggbb & 0x0000ff00) >> 8;
    NSUInteger blueComponent  = (aarrggbb & 0x000000ff);

    return [UIColor colorWithRed:(redComponent/255.0)
                           green:(greenComponent/255.0)
                            blue:(blueComponent/255.0)
                           alpha:(alphaComponent/255.0)];
}

@end

See http://undefinedvalue.com/2013/05/18/uicolor-category-specifying-packed-rgb-values for more info.