How can I create a UIColor from a hex string?
I've found the simplest way to do this is with a macro. Just include it in your header and it's available throughout your project.
#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]Also formatted version of this code:
#define UIColorFromRGB(rgbValue) \[UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 \ green:((float)((rgbValue & 0x00FF00) >> 8))/255.0 \ blue:((float)((rgbValue & 0x0000FF) >> 0))/255.0 \ alpha:1.0]Usage:
label.textColor = UIColorFromRGB(0xBC1128);Swift:
static func UIColorFromRGB(_ rgbValue: Int) -> UIColor! { return UIColor( red: CGFloat((Float((rgbValue & 0xff0000) >> 16)) / 255.0), green: CGFloat((Float((rgbValue & 0x00ff00) >> 8)) / 255.0), blue: CGFloat((Float((rgbValue & 0x0000ff) >> 0)) / 255.0), alpha: 1.0)}
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];}
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 Swift:
extension UIColor { convenience init?(hexString: String?) { let input: String! = (hexString ?? "") .replacingOccurrences(of: "#", with: "") .uppercased() var alpha: CGFloat = 1.0 var red: CGFloat = 0 var blue: CGFloat = 0 var green: CGFloat = 0 switch (input.count) { case 3 /* #RGB */: red = Self.colorComponent(from: input, start: 0, length: 1) green = Self.colorComponent(from: input, start: 1, length: 1) blue = Self.colorComponent(from: input, start: 2, length: 1) break case 4 /* #ARGB */: alpha = Self.colorComponent(from: input, start: 0, length: 1) red = Self.colorComponent(from: input, start: 1, length: 1) green = Self.colorComponent(from: input, start: 2, length: 1) blue = Self.colorComponent(from: input, start: 3, length: 1) break case 6 /* #RRGGBB */: red = Self.colorComponent(from: input, start: 0, length: 2) green = Self.colorComponent(from: input, start: 2, length: 2) blue = Self.colorComponent(from: input, start: 4, length: 2) break case 8 /* #AARRGGBB */: alpha = Self.colorComponent(from: input, start: 0, length: 2) red = Self.colorComponent(from: input, start: 2, length: 2) green = Self.colorComponent(from: input, start: 4, length: 2) blue = Self.colorComponent(from: input, start: 6, length: 2) break default: NSException.raise(NSExceptionName("Invalid color value"), format: "Color value \"%@\" is invalid. It should be a hex value of the form #RBG, #ARGB, #RRGGBB, or #AARRGGBB", arguments:getVaList([hexString ?? ""])) } self.init(red: red, green: green, blue: blue, alpha: alpha) } static func colorComponent(from string: String!, start: Int, length: Int) -> CGFloat { let substring = (string as NSString) .substring(with: NSRange(location: start, length: length)) let fullHex = length == 2 ? substring : "\(substring)\(substring)" var hexComponent: UInt64 = 0 Scanner(string: fullHex) .scanHexInt64(&hexComponent) return CGFloat(Double(hexComponent) / 255.0) }}