UIColor+HexString.m

//
//  UIColor+HexString.m
//
//  Created by Micah Hainline
//  http://stackoverflow.com/users/590840/micah-hainline
//

#import "UIColor+HexString.h"


@implementation UIColor (HexString)

+ (CGFloat)RA_colorComponentFrom:(NSString *)string start:(NSUInteger)start length:(NSUInteger)length {
    NSString *substring = [string substringWithRange:NSMakeRange(start, length)];
    NSString *fullHex = length == 2 ? substring : [NSString stringWithFormat:@"%@%@", substring, substring];
    unsigned hexComponent;
    [[NSScanner scannerWithString:fullHex] scanHexInt:&hexComponent];
    return hexComponent / 255.0;
}

+ (UIColor *)RA_colorWithHexString: (NSString *) hexString {
    if (hexString.length == 0) {
      return nil;
    }
    NSString *colorString = [[hexString stringByReplacingOccurrencesOfString:@"#" withString:@""] uppercaseString];
    CGFloat alpha, red, blue, green;
    switch ([colorString length]) {
      case 3: { // #RGB
        alpha = 1.0f;
        red   = [self RA_colorComponentFrom:colorString start:0 length:1];
        green = [self RA_colorComponentFrom:colorString start:1 length:1];
        blue  = [self RA_colorComponentFrom:colorString start:2 length:1];
        break;
      }
      case 4: { // #ARGB
        alpha = [self RA_colorComponentFrom:colorString start:0 length:1];
        red   = [self RA_colorComponentFrom:colorString start:1 length:1];
        green = [self RA_colorComponentFrom:colorString start:2 length:1];
        blue  = [self RA_colorComponentFrom:colorString start:3 length:1];
        break;
      }
      case 6: { // #RRGGBB
        alpha = 1.0f;
        red   = [self RA_colorComponentFrom: colorString start: 0 length: 2];
        green = [self RA_colorComponentFrom: colorString start: 2 length: 2];
        blue  = [self RA_colorComponentFrom: colorString start: 4 length: 2];
        break;
      }
      case 8: { // #AARRGGBB
        alpha = [self RA_colorComponentFrom: colorString start: 0 length: 2];
        red   = [self RA_colorComponentFrom: colorString start: 2 length: 2];
        green = [self RA_colorComponentFrom: colorString start: 4 length: 2];
        blue  = [self RA_colorComponentFrom: colorString start: 6 length: 2];
        break;
      }
      default:
        return nil;
    }
    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}

@end