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

Create elegant extension for UIColor:

extension UIColor {

convenience init(string: String) {

        var uppercasedString = string.uppercased()
        uppercasedString.remove(at: string.startIndex)

        var rgbValue: UInt32 = 0
        Scanner(string: uppercasedString).scanHexInt32(&rgbValue)

        let red = CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0
        let green = CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0
        let blue = CGFloat(rgbValue & 0x0000FF) / 255.0

        self.init(red: red, green: green, blue: blue, alpha: 1)
    }
}

Create red color:

let red = UIColor(string: "#ff0000") 

Answer 2

I created a convenience init for that:

extension UIColor {
convenience init(hex: String, alpha: CGFloat)
{
    let redH = CGFloat(strtoul(hex.substringToIndex(advance(hex.startIndex,2)), nil, 16))
    let greenH = CGFloat(strtoul(hex.substringWithRange(Range<String.Index>(start: advance(hex.startIndex, 2), end: advance(hex.startIndex, 4))), nil, 16))
    let blueH = CGFloat(strtoul(hex.substringFromIndex(advance(hex.startIndex,4)), nil, 16))

    self.init(red: redH/255, green: greenH/255, blue: blueH/255, alpha: alpha)
}
}

then you can create an UIColor anywhere in your project just like this:

UIColor(hex: "ffe3c8", alpha: 1)

hope this helps...

Answer 3

You can create extension class of UIColor as:-

extension UIColor {

// MARK: - getColorFromHex /** This function will convert the color Hex code to RGB.

- parameter color  hex string.

- returns: RGB color code.
*/
class func getColorFromHex(hexString:String)->UIColor{

    var rgbValue : UInt32 = 0
    let scanner:NSScanner =  NSScanner(string: hexString)

    scanner.scanLocation = 1
    scanner.scanHexInt(&rgbValue)

    return UIColor(red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0, green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0, blue: CGFloat(rgbValue & 0x0000FF) / 255.0, alpha: CGFloat(1.0))
}

}

Answer 4

updated for swift 1.2

class func colorWithHexString (hex:String) -> UIColor {
    var cString: NSString = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString

    if (cString.hasPrefix("#")) {
        cString = cString.substringFromIndex(1)
    }

    if (count(cString as String) != 6) {
        return UIColor.grayColor()
    }

    var rString: String = cString.substringToIndex(2)
    var gString: String = (cString.substringFromIndex(2) as NSString).substringToIndex(2)
    var bString: String = (cString.substringFromIndex(4) as NSString).substringToIndex(2)

    var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
    NSScanner(string: rString).scanHexInt(&r)
    NSScanner(string: gString).scanHexInt(&g)
    NSScanner(string: bString).scanHexInt(&b)
    return UIColor(red: CGFloat(Float(r) / 255.0), green: CGFloat(Float(g) / 255.0), blue: CGFloat(Float(b) / 255.0), alpha: CGFloat(1))

}

Answer 5

I've got a solution that is 100% compatible with the hex format strings used by Android, which I found very helpful when doing cross-platform mobile development. It lets me use one color palate for both platforms. Feel free to reuse without attribution, or under the Apache license if you prefer.

#import "UIColor+HexString.h"

@interface UIColor(HexString)

+ (UIColor *) colorWithHexString: (NSString *) hexString;
+ (CGFloat) colorComponentFrom: (NSString *) string start: (NSUInteger) start length: (NSUInteger) length;

@end


@implementation UIColor(HexString)

+ (UIColor *) colorWithHexString: (NSString *) hexString {
    NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];
    CGFloat alpha, red, blue, green;
    switch ([colorString length]) {
        case 3: // #RGB
            alpha = 1.0f;
            red   = [self colorComponentFrom: colorString start: 0 length: 1];
            green = [self colorComponentFrom: colorString start: 1 length: 1];
            blue  = [self colorComponentFrom: colorString start: 2 length: 1];
            break;
        case 4: // #ARGB
            alpha = [self colorComponentFrom: colorString start: 0 length: 1];
            red   = [self colorComponentFrom: colorString start: 1 length: 1];
            green = [self colorComponentFrom: colorString start: 2 length: 1];
            blue  = [self colorComponentFrom: colorString start: 3 length: 1];          
            break;
        case 6: // #RRGGBB
            alpha = 1.0f;
            red   = [self colorComponentFrom: colorString start: 0 length: 2];
            green = [self colorComponentFrom: colorString start: 2 length: 2];
            blue  = [self colorComponentFrom: colorString start: 4 length: 2];                      
            break;
        case 8: // #AARRGGBB
            alpha = [self colorComponentFrom: colorString start: 0 length: 2];
            red   = [self colorComponentFrom: colorString start: 2 length: 2];
            green = [self colorComponentFrom: colorString start: 4 length: 2];
            blue  = [self colorComponentFrom: colorString start: 6 length: 2];                      
            break;
        default:
            [NSException raise:@"Invalid color value" format: @"Color value %@ is invalid.  It should be a hex value of the form #RBG, #ARGB, #RRGGBB, or #AARRGGBB", hexString];
            break;
    }
    return [UIColor colorWithRed: red green: green blue: blue alpha: alpha];
}

+ (CGFloat) 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;
}

@end 

Answer 6

I found a good UIColor category for this, UIColor+PXExtensions.

Usage: UIColor *mycolor = [UIColor pxColorWithHexValue:@"#BADA55"];

And, just in case the link to my gist fails, here is the actual implementation code:

//
//  UIColor+PXExtensions.m
//

#import "UIColor+UIColor_PXExtensions.h"

@implementation UIColor (UIColor_PXExtensions)

+ (UIColor*)pxColorWithHexValue:(NSString*)hexValue
{
    //Default
    UIColor *defaultResult = [UIColor blackColor];

    //Strip prefixed # hash
    if ([hexValue hasPrefix:@"#"] && [hexValue length] > 1) {
        hexValue = [hexValue substringFromIndex:1];
    }

    //Determine if 3 or 6 digits
    NSUInteger componentLength = 0;
    if ([hexValue length] == 3)
    {
        componentLength = 1;
    }
    else if ([hexValue length] == 6)
    {
        componentLength = 2;
    }
    else
    {
        return defaultResult;
    }

    BOOL isValid = YES;
    CGFloat components[3];

    //Seperate the R,G,B values
    for (NSUInteger i = 0; i < 3; i++) {
        NSString *component = [hexValue substringWithRange:NSMakeRange(componentLength * i, componentLength)];
        if (componentLength == 1) {
            component = [component stringByAppendingString:component];
        }
        NSScanner *scanner = [NSScanner scannerWithString:component];
        unsigned int value;
        isValid &= [scanner scanHexInt:&value];
        components[i] = (CGFloat)value / 256.0f;
    }

    if (!isValid) {
        return defaultResult;
    }

    return [UIColor colorWithRed:components[0]
                           green:components[1]
                            blue:components[2]
                           alpha:1.0];
}

@end