How can I create a UIColor from a hex string?

Question

How can I create a UIColor from a hexadecimal string format, such as #00FF00?

Answer 1

There's a nice post on how to tackle the OP's question of extracting a UIColor from a hex string. The solution presented below is different from others because it supports string values that may include '0x' or '#' prefixed to the hex string representation... (see usage)

Here's the main bit..

- (UIColor *)getUIColorObjectFromHexString:(NSString *)hexStr alpha:(CGFloat)alpha
{
  // Convert hex string to an integer
  unsigned int hexint = [self intFromHexString:hexStr];

  // Create color object, specifying alpha as well
  UIColor *color =
    [UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255
    green:((CGFloat) ((hexint & 0xFF00) >> 8))/255
    blue:((CGFloat) (hexint & 0xFF))/255
    alpha:alpha];

  return color;
}

Helper method..

- (unsigned int)intFromHexString:(NSString *)hexStr
{
  unsigned int hexInt = 0;

  // Create scanner
  NSScanner *scanner = [NSScanner scannerWithString:hexStr];

  // Tell scanner to skip the # character
  [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"#"]];

  // Scan hex value
  [scanner scanHexInt:&hexInt];

  return hexInt;
}

Usage:

NSString *hexStr1 = @"123ABC";
NSString *hexStr2 = @"#123ABC";
NSString *hexStr3 = @"0x123ABC";

UIColor *color1 = [self getUIColorObjectFromHexString:hexStr1 alpha:.9];
NSLog(@"UIColor: %@", color1);

UIColor *color2 = [self getUIColorObjectFromHexString:hexStr2 alpha:.9];
NSLog(@"UIColor: %@", color2);

UIColor *color3 = [self getUIColorObjectFromHexString:hexStr3 alpha:.9];
NSLog(@"UIColor: %@", color3);

Complete Reference Article

Swift 2+

I've ported this solution to Swift 2.2. Note that I've changed the alpha parameter to an optional value with a default set to 1.0. I've also updated the int type to UInt32 as required by the NSScanner class in Swift 2.2.

func colorWithHexString(hexString: String, alpha:CGFloat? = 1.0) -> UIColor {

    // Convert hex string to an integer
    let hexint = Int(self.intFromHexString(hexString))
    let red = CGFloat((hexint & 0xff0000) >> 16) / 255.0
    let green = CGFloat((hexint & 0xff00) >> 8) / 255.0
    let blue = CGFloat((hexint & 0xff) >> 0) / 255.0 
    let alpha = alpha!

    // Create color object, specifying alpha as well
    let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
    return color
}

func intFromHexString(hexStr: String) -> UInt32 {
    var hexInt: UInt32 = 0
    // Create scanner
    let scanner: NSScanner = NSScanner(string: hexStr)
    // Tell scanner to skip the # character
    scanner.charactersToBeSkipped = NSCharacterSet(charactersInString: "#")
    // Scan hex value
    scanner.scanHexInt(&hexInt)
    return hexInt
}

Swift 4+

Using the same logic with changes applied for swift 4,

func colorWithHexString(hexString: String, alpha:CGFloat? = 1.0) -> UIColor {

    // Convert hex string to an integer
    let hexint = Int(self.intFromHexString(hexStr: hexString))
    let red = CGFloat((hexint & 0xff0000) >> 16) / 255.0
    let green = CGFloat((hexint & 0xff00) >> 8) / 255.0
    let blue = CGFloat((hexint & 0xff) >> 0) / 255.0
    let alpha = alpha!

    // Create color object, specifying alpha as well
    let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
    return color
}

func intFromHexString(hexStr: String) -> UInt32 {
    var hexInt: UInt32 = 0
    // Create scanner
    let scanner: Scanner = Scanner(string: hexStr)
    // Tell scanner to skip the # character
    scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
    // Scan hex value
    scanner.scanHexInt32(&hexInt)
    return hexInt
}

Color Hex References

HTML Color Names and Codes

Color Hex Color Codes

Answer 2

extension UIColor {
    convenience init(hexaString: String, alpha: CGFloat = 1) {
        let chars = Array(hexaString.characters)
        self.init(red:   CGFloat(strtoul(String(chars[1...2]),nil,16))/255,
                  green: CGFloat(strtoul(String(chars[3...4]),nil,16))/255,
                  blue:  CGFloat(strtoul(String(chars[5...6]),nil,16))/255,
                  alpha: alpha)}
}

---

Usage:

let redColor       = UIColor(hexaString: "#FF0000")              // r 1,0 g 0,0 b 0,0 a 1,0
let transparentRed = UIColor(hexaString: "#FF0000", alpha: 0.5)  // r 1,0 g 0,0 b 0,0 a 0,5

Answer 3

I like to ensure the alpha besides the color, so i write my own category

+ (UIColor *) colorWithHex:(int)color {

    float red = (color & 0xff000000) >> 24;
    float green = (color & 0x00ff0000) >> 16;
    float blue = (color & 0x0000ff00) >> 8;
    float alpha = (color & 0x000000ff);

    return [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:alpha/255.0];
}

easy to use like this

[UIColor colorWithHex:0xFF0000FF]; //Red
[UIColor colorWithHex:0x00FF00FF]; //Green
[UIColor colorWithHex:0x00FF00FF]; //Blue
[UIColor colorWithHex:0x0000007F]; //transparent black

Answer 4

Another implementation allowing strings like "FFF" or "FFFFFF" and using alpha:

+ (UIColor *) colorFromHexString:(NSString *)hexString alpha: (CGFloat)alpha{
    NSString *cleanString = [hexString stringByReplacingOccurrencesOfString:@"#" withString:@""];
    if([cleanString length] == 3) {
        cleanString = [NSString stringWithFormat:@"%@%@%@%@%@%@",
                       [cleanString substringWithRange:NSMakeRange(0, 1)],[cleanString substringWithRange:NSMakeRange(0, 1)],
                       [cleanString substringWithRange:NSMakeRange(1, 1)],[cleanString substringWithRange:NSMakeRange(1, 1)],
                       [cleanString substringWithRange:NSMakeRange(2, 1)],[cleanString substringWithRange:NSMakeRange(2, 1)]];
    }
    if([cleanString length] == 6) {
        cleanString = [cleanString stringByAppendingString:@"ff"];
    }

    unsigned int baseValue;
    [[NSScanner scannerWithString:cleanString] scanHexInt:&baseValue];

    float red = ((baseValue >> 24) & 0xFF)/255.0f;
    float green = ((baseValue >> 16) & 0xFF)/255.0f;
    float blue = ((baseValue >> 8) & 0xFF)/255.0f;

    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}

Answer 5

Swift equivalent of @Tom's answer, although receiving RGBA Int value to support transparency:

func colorWithHex(aHex: UInt) -> UIColor
{
    return UIColor(red: CGFloat((aHex & 0xFF000000) >> 24) / 255,
        green: CGFloat((aHex & 0x00FF0000) >> 16) / 255,
        blue: CGFloat((aHex & 0x0000FF00) >> 8) / 255,
        alpha: CGFloat((aHex & 0x000000FF) >> 0) / 255)
}

//usage
var color = colorWithHex(0x7F00FFFF)

And if you want to be able to use it from string you could use strtoul:

var hexString = "0x7F00FFFF"

let num = strtoul(hexString, nil, 16)

var colorFromString = colorWithHex(num)

Answer 6

A concise solution:

// Assumes input like "#00FF00" (#RRGGBB).
+ (UIColor *)colorFromHexString:(NSString *)hexString {
    unsigned rgbValue = 0;
    NSScanner *scanner = [NSScanner scannerWithString:hexString];
    [scanner setScanLocation:1]; // bypass '#' character
    [scanner scanHexInt:&rgbValue];
    return [UIColor colorWithRed:((rgbValue & 0xFF0000) >> 16)/255.0 green:((rgbValue & 0xFF00) >> 8)/255.0 blue:(rgbValue & 0xFF)/255.0 alpha:1.0];
}