I made a category on UIColor which allows to create color from hex code (eg.: #498ea8). I have tried to use different methods to get number from hex string, but all of them was to slow, something about 0.022 - 0.040 ms. This is the fastest way I've found

UIColor+HashParser.h

//
//  UIColor+HashParser.h
//
//  Created by Vojtech Micka on 11/19/12.
//  Copyright (c) 2012 All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UIColor (HexParser)

+ (UIColor *) colorWithHex:(NSString *)hex andAlpha:(CGFloat)alpha;

@end

UIColor+HexParser.m

//
//  UIColor+HashParser.m
//
//  Created by Vojtech Micka on 11/19/12.
//  Copyright (c) 2012 All rights reserved.
//

#import "UIColor+HexParser.h"

@implementation UIColor (HexParser)

+ (UIColor *) colorWithHex:(NSString *)hex andAlpha:(CGFloat)alpha {
    
    if ( [hex hasPrefix:@"#"] ) hex = [hex substringFromIndex:1];
    
    size_t lengthOfChars = 6, colorMax = 255;
    
    unsigned char * colors = (unsigned char *) malloc(sizeof(unsigned char) * 3);
    unichar * chars = (unichar *) malloc(sizeof(unichar) * lengthOfChars);
    
    unichar temp;
    
    [hex getCharacters:chars range:(NSRange) {0, [hex length]}];
    
    for ( int i = 0; i < lengthOfChars; i += 2 ) {
        
        temp = *(chars + i);
        
        if ( temp >= '0' && temp <= '9' ) {
            *(colors + i/2) = (unsigned char) (temp - '0') << 4;
        } else if ( temp >= 'a' && temp <= 'f' ) {
            *(colors + i/2) = (unsigned char) (temp - 'a' + 10) << 4;
        } else if ( temp >= 'A' && temp <= 'F' ) {
            *(colors + i/2) = (unsigned char) (temp - 'A' + 10) << 4;
        } else {
            *(colors + i/2) = 0;
        }
        
        temp = *(chars + i + 1);
        
        if ( temp >= '0' && temp <= '9' ) {
            *(colors + i/2) += (unsigned char) (temp - '0');
        } else if ( temp >= 'a' && temp <= 'f' ) {
            *(colors + i/2) += (unsigned char) (temp - 'a' + 10);
        } else if ( temp >= 'A' && temp <= 'F' ) {
            *(colors + i/2) += (unsigned char) (temp - 'A' + 10);
        }
    }
    
    return [UIColor colorWithRed:((CGFloat) *(colors + 0) / colorMax)
                           green:((CGFloat) *(colors + 1) / colorMax)
                            blue:((CGFloat) *(colors + 2) / colorMax)
                           alpha:alpha];
}

@end