UIColor not working with RGBA values

问题:

I am trying to change the text colour in a UITextField using the following code (RGBA value) however it just appears white, or clear, I'm not too sure as the background is white itself.

passwordTextField.textColor = UIColor(red: CGFloat(202.0), green: CGFloat(228.0), blue: CGFloat(230.0), alpha: CGFloat(100.0))

passwordTextField.returnKeyType = UIReturnKeyType.Done
passwordTextField.placeholder = "Password"
passwordTextField.backgroundColor = UIColor.clearColor()
passwordTextField.borderStyle = UITextBorderStyle.RoundedRect
passwordTextField.font = UIFont(name: "Avenir Next", size: 14)
passwordTextField.textAlignment = NSTextAlignment.Center
passwordTextField.secureTextEntry = true

回答1:

RGB values for UIColor are between 0 and 1 (see the documentation "specified as a value from 0.0 to 1.0")

You need to divide your numbers by 255:

passwordTextField.textColor = UIColor(red: CGFloat(202.0/255.0), green: CGFloat(228.0/255.0), blue: CGFloat(230.0/255.0), alpha: CGFloat(1.0))

Another thing, you don't need to create CGFloats:

passwordTextField.textColor = UIColor(red:202.0/255.0, green:228.0/255.0, blue:230.0/255.0, alpha:1.0)

回答2:

Using convenience init ( code like a pro )

Step 1

extension UIColor {
    convenience init(r: CGFloat, g: CGFloat, b: CGFloat) {
        self.init(red: r/255, green: g/255, blue: b/255, alpha: 1)
    }
}

Usage

//let color = UIColor(red: 202/255, green: 228/255, blue: 230/255, alpha: 1) ☠️
let color = UIColor(r: 202, g: 228, b: 230) //