How to convert UIColor to HEX and display in NSLog

Question

I have checked several links on how to convert UIColor codes to HEX however I am not sure on how to call to the method to display them in NSLog. I haven't got the reputation to comment so posting as a question is my last resort. I want it to display when I run my app in the log.

Second, where do I input the RGB color number ( R = 30, G = 171, B = 13)? I see that all examples use Array [0], [1], [2] which normally refers to index position, so where do I add the color values?

I have this code:

- (NSString *) hexFromUIColor:(UIColor *)color {      if (CGColorGetNumberOfComponents(color.CGColor) < 4) {         const CGFloat *components = CGColorGetComponents(color.CGColor);         color = [UIColor colorWithRed:components[30] green:components[141] blue:components[13] alpha:components[1]];     }     if (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) != kCGColorSpaceModelRGB) {         return [NSString stringWithFormat:@"#FFFFFF"];     }     return [NSString stringWithFormat:@"#%02X%02X%02X", (int)((CGColorGetComponents(color.CGColor))[0]*255.0), (int)((CGColorGetComponents(color.CGColor))[1]*255.0), (int)((CGColorGetComponents(color.CGColor))[2]*255.0)];  } 

Links I have checked:

hex color from uicolor

How to convert HEX RGB color codes to UIColor?

I have tried to call the method in viewDidLoad however it wont work without UIColor. I am sure it's something simple.

Thanks to anyone who answers.

What is the code I use in my viewDidLoad to call to this method in order to display in NSLog?

Answer 1

Swift 5:

func hexStringFromColor(color: UIColor) -> String {     let components = color.cgColor.components     let r: CGFloat = components?[0] ?? 0.0     let g: CGFloat = components?[1] ?? 0.0     let b: CGFloat = components?[2] ?? 0.0      let hexString = String.init(format: "#%02lX%02lX%02lX", lroundf(Float(r * 255)), lroundf(Float(g * 255)), lroundf(Float(b * 255)))     print(hexString)     return hexString  }  func colorWithHexString(hexString: String) -> UIColor {     var colorString = hexString.trimmingCharacters(in: .whitespacesAndNewlines)     colorString = colorString.replacingOccurrences(of: "#", with: "").uppercased()      print(colorString)     let alpha: CGFloat = 1.0     let red: CGFloat = self.colorComponentFrom(colorString: colorString, start: 0, length: 2)     let green: CGFloat = self.colorComponentFrom(colorString: colorString, start: 2, length: 2)     let blue: CGFloat = self.colorComponentFrom(colorString: colorString, start: 4, length: 2)      let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)     return color }  func colorComponentFrom(colorString: String, start: Int, length: Int) -> CGFloat {      let startIndex = colorString.index(colorString.startIndex, offsetBy: start)     let endIndex = colorString.index(startIndex, offsetBy: length)     let subString = colorString[startIndex..<endIndex]     let fullHexString = length == 2 ? subString : "\(subString)\(subString)"     var hexComponent: UInt32 = 0      guard Scanner(string: String(fullHexString)).scanHexInt32(&hexComponent) else {         return 0     }     let hexFloat: CGFloat = CGFloat(hexComponent)     let floatValue: CGFloat = CGFloat(hexFloat / 255.0)     print(floatValue)     return floatValue } 

How to use

let red =  CGFloat(30.0) let green =  CGFloat(171.0) let blue =  CGFloat(13.0) let alpha =  CGFloat(1.0)  let color = UIColor(red: CGFloat(red/255.0), green: CGFloat(green/255.0), blue: CGFloat(blue / 255.0), alpha: alpha) let colorCode = self.hexStringFromColor(color: color) print(colorCode)  let resultColor = self.colorWithHexString(hexString: colorCode) print(resultColor) 

Objective-C:

- (NSString *)hexStringFromColor:(UIColor *)color {     const CGFloat *components = CGColorGetComponents(color.CGColor);      CGFloat r = components[0];     CGFloat g = components[1];     CGFloat b = components[2];      return [NSString stringWithFormat:@"#%02lX%02lX%02lX",             lroundf(r * 255),             lroundf(g * 255),             lroundf(b * 255)]; } 

After getting hex code string, Call below method to get UIColor

- (UIColor *) colorWithHexString: (NSString *) hexString {     NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];      NSLog(@"colorString :%@",colorString);     CGFloat alpha, red, blue, green;      // #RGB     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];      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; } 

How to use

// ( R = 30, G = 171, B = 13)?  CGFloat red = 30.0; CGFloat green = 171.0; CGFloat blue = 13.0;  CGFloat alpha = 255.0 UIColor *color = [UIColor colorWithRed:(red/255.0) green:(green/255.0) blue:(blue/255.0) alpha:(alpha/255.0)]; NSString *colorCode = [self hexStringFromColor:color]; NSLog(@"Color Code: %@", colorCode);  UIColor *resultColor = [self colorWithHexString:colorCode]; 

Answer 2

And finally the version which works with alpha-component and uses right multiplier

extension UIColor {     var hexString: String? {         var red: CGFloat = 0         var green: CGFloat = 0         var blue: CGFloat = 0         var alpha: CGFloat = 0          let multiplier = CGFloat(255.999999)          guard self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) else {             return nil         }          if alpha == 1.0 {             return String(                 format: "#%02lX%02lX%02lX",                 Int(red * multiplier),                 Int(green * multiplier),                 Int(blue * multiplier)             )         }         else {             return String(                 format: "#%02lX%02lX%02lX%02lX",                 Int(red * multiplier),                 Int(green * multiplier),                 Int(blue * multiplier),                 Int(alpha * multiplier)             )         }     } }