Extending UIColor ... and extend more as needed. Hex conversion from http://stackoverflow.com/questions/4265161/how-to-convert-hexadecimal-to-rgb

UIColor+Colours.h

//
//  UIColor+Colours.h
//
//  Created by Soemarko Ridwan on 25/05/13.
//  Copyright (c) 2013 Soemarko Ridwan. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UIColor (Colours)

// accepts 0xff00aa
+(UIColor *)colorWithRGBHex:(UInt32)hex withAlpha:(float)alpha;

+(UIColor *)whiteColorWithAlpha:(float)alpha;
+(UIColor *)blackColorWithAlpha:(float)alpha;

+(UIColor *)antiFlashWhiteColor;
+(UIColor *)blackOliveColor;

@end

UIColor+Colours.m

//
//  UIColor+Colours.m
//
//  Created by Soemarko Ridwan on 25/05/13.
//  Copyright (c) 2013 Soemarko Ridwan. All rights reserved.
//

#import "UIColor+Colours.h"

@implementation UIColor (Colours)

+(UIColor *)colorWithRGBHex:(UInt32)hex withAlpha:(float)alpha {
	int r = (hex >> 16) & 0xFF;
	int g = (hex >> 8) & 0xFF;
	int b = (hex) & 0xFF;

	return [UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:alpha];
}

+(UIColor *)whiteColorWithAlpha:(float)alpha {
	return [UIColor colorWithRed:255.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:alpha];
}

+(UIColor *)blackColorWithAlpha:(float)alpha {
	return [UIColor colorWithRed:0 green:0 blue:0 alpha:alpha];
}

+(UIColor *)antiFlashWhiteColor {
	return [UIColor colorWithRed:242.0/255.0 green:243.0/255.0 blue:244.0/255.0 alpha:1.0];
}

+(UIColor *)blackOliveColor {
	return [UIColor colorWithRed:59.0/255.0 green:60.0/255.0 blue:54.0/255.0 alpha:1.0];
}

@end