【Swift】How to change the color of Text

＊Swift5, Xcode ver 12.1

The code changes the Text color in System color, RGB, and color code.
Please refer to it when changing the text color of labels and text.

Specify a color using System color

@IBOutlet weak var label: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()
　　　　　// white
　　　　　label.textColor = UIColor.white
　　　　　// black
　　　　　label.textColor = UIColor.black
　　　　　// red
         label.textColor = UIColor.red
　　　　　//Available on iOS 13 and above
　　　　　label.textColor = UIColor.systemGray2
        label.textColor = UIColor.secondaryLabel
    }

Select Text color from Storyboard to see a list of other colors

Specify the color with RGB (0 ~ 1.0)

Specify the RGB value of Swift’s UI color from 0 to 1.0 instead of 255 steps.
Write the following code in viewDidLoad

// rgba = UIColor (red, green, blue, transparency)
// Set alpha to 0.0 to make Text transparent
let rgba = UIColor(red: 0.1, green: 0.7, blue: 0.9, alpha: 1.0)
label.textColor = rgba

Specify the color in RGB (0 to 255)

Even though I know the RGB value from 0 to 255, I don’t want to use it too much because it is troublesome to calculate and adjust each time if it is RGB (0 to 1.0) mentioned above. .. ..
In such a case, it is convenient to use the RGB value as it is by using a code that divides the known RGB value by 255. Write the following code in viewDidLoad

// rgba = UIColor (red, green, blue, transparency)
// Set alpha to 0.0 to make Text transparent
let rgba = UIColor(red: 129/255, green: 216/255, blue: 208/255, alpha: 1.0)
explain.textColor = rgba

Specify the color code

However, it is easier to specify by color code, so prepare the following extensions.
It is recommended to make an extension once because it is quite convenient because it can be used in various situations.

Create a new SwiftFile

File → New → File … → Select Swift File and enter an appropriate name such as UIColorHex in Save as → Decide the save destination and Create
The following code in the created file Paste.

import UIKit

extension UIColor {
    convenience init(hex: String, alpha: CGFloat = 1.0) {
        let v = Int("000000" + hex, radix: 16) ?? 0
        let r = CGFloat(v / Int(powf(256, 2)) % 256) / 255
        let g = CGFloat(v / Int(powf(256, 1)) % 256) / 255
        let b = CGFloat(v / Int(powf(256, 0)) % 256) / 255
        self.init(red: r, green: g, blue: b, alpha: min(max(alpha, 0), 1))
    }
}

Describe the following in viewDidLoad of the class you want to use
Call UIColor and put the color code without # in hex to use

label.textColor = UIColor(hex: "333333")
label.textColor = UIColor(hex: "333333", alpha: 1.0)

Click here to specify the color code in the custom class

import UIKit

class CustomLabelText: UILabel {

    override init(frame: CGRect) {
        super.init(frame: frame)
        customText()
      }
      required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        customText()
      }
      
      override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        customText()
      }
      
      private func customText() {
        textColor = UIColor(hex: "333333", alpha: 1.0)
        font = UIFont(name: "Helvetica Neue", size: 17)
      }
}

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