How do I create a UIColor from RGBA?

Question

I want to use NSAttributedString in my project, but when I\'m trying to set color, which isn\'t from the standard set (redColor, blackColor

Answer 1

Please try the code

[attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor colorWithRed:77.0/255.0f green:104.0/255.0f blue:159.0/255.0f alpha:1.0] range:NSMakeRange(0, attributedString.length)];

like

Label.textColor=[UIColor colorWithRed:77.0/255.0f green:104.0/255.0f blue:159.0/255.0f alpha:1.0];  

UIColor's RGB components are scaled between 0 and 1, not up to 255.

Answer 2

Your values are incorrect, you need to divide each color value by 255.0.

[UIColor colorWithRed:66.0f/255.0f
                green:79.0f/255.0f
                 blue:91.0f/255.0f
                alpha:1.0f];

The docs state:

+ (UIColor *)colorWithRed:(CGFloat)red
                    green:(CGFloat)green
                     blue:(CGFloat)blue
                    alpha:(CGFloat)alpha

Parameters

red The red component of the color object, specified as a value from 0.0 to 1.0.

green The green component of the color object, specified as a value from 0.0 to 1.0.

blue The blue component of the color object, specified as a value from 0.0 to 1.0.

alpha The opacity value of the color object, specified as a value from 0.0 to 1.0.

Reference here.

Answer 3

UIColor uses a range from 0 to 1.0, not integers to 255.. Try this:

// create color
UIColor *color = [UIColor colorWithRed:66/255.0
                                 green:79/255.0
                                  blue:91/255.0
                                 alpha:1];

// use in attributed string
[attributedString addAttribute:NSForegroundColorAttributeName
                         value:color
                         range:NSMakeRange(0, attributedString.length)];

Answer 4

One of my favourite macros, no project without:

#define RGB(r, g, b) [UIColor colorWithRed:(float)r / 255.0 green:(float)g / 255.0 blue:(float)b / 255.0 alpha:1.0]
#define RGBA(r, g, b, a) [UIColor colorWithRed:(float)r / 255.0 green:(float)g / 255.0 blue:(float)b / 255.0 alpha:a]

Using like:

[attributedString addAttribute:NSForegroundColorAttributeName
                         value:RGB(66, 79, 91)
                         range:NSMakeRange(0, attributedString.length)];

Answer 5

Since @Jaswanth Kumar asked, here's the Swift version from LSwift:

extension UIColor {
    convenience init(rgb:UInt, alpha:CGFloat = 1.0) {
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(alpha)
        )
    }
}

Usage: let color = UIColor(rgb: 0x112233)