How to Convert Uicolor to Swiftui's Color

How to convert UIColor to SwiftUI‘s Color

Starting with beta 5, you can create a Color from a UIColor:

Color(UIColor.systemBlue)

Convert SwiftUI Color to UIColor

Basically, Apple doesn't intend for you to do this conversion. SwiftUI's Color is a View, and the design of the framework is that data flows to a View, which is then displayed. You are never supposed to extract data back from a View.

If you find yourself needing to use the components of a color, you should work with UIColor, and then convert to Color at the time you are ready to display it.

If you are trying to get the components of system colors like Color.red, I believe they are the same as the adaptive UIColor.systemRed, which does have accessible components.

Standard Colors documentation

Getting Dynamic UIColor from SwiftUI Color (light and dark mode)

I don't think what you want is possible. To achieve that you needed an initializer of Color that takes a light and dark variant and a way to resolve to a cgColor given a certain interface style (both not possible afaik). But your common ground could be the color name of your color from the asset catalogue and you could derive your SwiftUI/UIKit colors from the identifier.

struct ColorId: RawRepresentable, Equatable, Hashable {
    let rawValue: String

    init(_ rawValue: String) {
        self.init(rawValue: rawValue)
    }

    init(rawValue: String) {
        self.rawValue = rawValue
    }

    static let primaryText = ColorId("asset_name_of_primary_text_color")
}

extension ColorId {
    var color: Color { Color(rawValue) }
    var uiColor: UIColor? { UIColor(named: rawValue) }
}

struct SomeView: View {
    let textColor = ColorId.primaryText
    var body: some View { 
        Text("Text")
            .foregroundColor(textColor.color)  
    }
}

final class SomeUIView: UILabel {
    private let textColorId: ColorId

    init(textColorId: ColorId) {
        self.textColorId = textColorId
        super.init(frame: .zero)
        self.textColor = textColorId.uiColor
    }
    required init?(coder: NSCoder) { fatalError("need a color id") }
}

Then you pass around your color ids and get the UIColor or Color values when you need them. If you use something like RSwift you could also just pass around the ColorResource's.

How to convert UIColor to HEX and display in NSLog

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];

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