Swift Uicolor Initializer - Compiler Error Only When Targeting Iphone5S

Swift UIColor initializer - compiler error only when targeting iPhone5s

It probably has to do with a mismatch between Float and Double. Basically, if the arguments are expected to be CGFloats, you need to pass CGFloats.

let color = UIColor(red: CGFloat(red), green: CGFloat(green), blue: CGFloat(blue), alpha: CGFloat(alpha))

What's important to understand here is that CGFloat is defined as Float on 32 bit platforms, and Double on 64 bit platforms. So, if you're explicitly using Floats, Swift won't have a problem with this on 32 Bit platforms, but will produce an error on 64 bit.

Extra argument in call when using var

Answer was: Swift UIColor initializer - compiler error only when targeting iPhone5s

Use float instead of integers.

UIColor(red: 1.0, green:0.0, blue: 0.0, alpha:alpha)

UIColor initializer (cannot find an initializer of type 'UIColor' that accepts ....) error

Use CGFloat not Float

Check the API docs when you get an error like this

Issue with String initializer in Swift when using format parameter

Foundation has to be imported before using String.
String is a Foundation type in swift.

I was corrected by Matt below in the comments.
String is built into swift and String(format: is in foundation.
I guess that's why the docs didn't show it as such.
Thank you for the correction.

arc4random and arm64 with swift

The parameters for UIColor(hue: saturation: brightness: alpha) are all of type CGFloat. The problem you're seeing is that CGFloat is aliased to different types depending on the architecture. For 32-bit ARM, (iPhone 4S and 5), it's a Float internally, but for arm64, it's actually a Double. If you just use CGFloat instead of Float for your type casts it will work fine:

var hue = CGFloat(arc4random() % 256) / 256.0;
var saturation = CGFloat(arc4random() % 128) / 256.0 + 0.5;
var brightness = CGFloat(arc4random() % 128) / 256.0 + 0.5;
self.color = UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1);

Swift - Could not find an overload... & Cannot convert the expression's type

For both errors, try creating new CGFloats.

CGFloat(0.5)
CFFloat(scaledWidth)

How to use hex color values

#ffffff are actually 3 color components in hexadecimal notation - red ff, green ff and blue ff. You can write hexadecimal notation in Swift using 0x prefix, e.g 0xFF

To simplify the conversion, let's create an initializer that takes integer (0 - 255) values:

extension UIColor {
   convenience init(red: Int, green: Int, blue: Int) {
       assert(red >= 0 && red <= 255, "Invalid red component")
       assert(green >= 0 && green <= 255, "Invalid green component")
       assert(blue >= 0 && blue <= 255, "Invalid blue component")

       self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: 1.0)
   }

   convenience init(rgb: Int) {
       self.init(
           red: (rgb >> 16) & 0xFF,
           green: (rgb >> 8) & 0xFF,
           blue: rgb & 0xFF
       )
   }
}

Usage:

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF)
let color2 = UIColor(rgb: 0xFFFFFF)

How to get alpha?

Depending on your use case, you can simply use the native UIColor.withAlphaComponent method, e.g.

let semitransparentBlack = UIColor(rgb: 0x000000).withAlphaComponent(0.5)

Or you can add an additional (optional) parameter to the above methods:

convenience init(red: Int, green: Int, blue: Int, a: CGFloat = 1.0) {
    self.init(
        red: CGFloat(red) / 255.0,
        green: CGFloat(green) / 255.0,
        blue: CGFloat(blue) / 255.0,
        alpha: a
    )
}

convenience init(rgb: Int, a: CGFloat = 1.0) {
    self.init(
        red: (rgb >> 16) & 0xFF,
        green: (rgb >> 8) & 0xFF,
        blue: rgb & 0xFF,
        a: a
    )
}

(we cannot name the parameter alpha because of a name collision with the existing initializer).

Called as:

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF, a: 0.5)
let color2 = UIColor(rgb: 0xFFFFFF, a: 0.5)

To get the alpha as an integer 0-255, we can

convenience init(red: Int, green: Int, blue: Int, a: Int = 0xFF) {
    self.init(
        red: CGFloat(red) / 255.0,
        green: CGFloat(green) / 255.0,
        blue: CGFloat(blue) / 255.0,
        alpha: CGFloat(a) / 255.0
    )
}

// let's suppose alpha is the first component (ARGB)
convenience init(argb: Int) {
    self.init(
        red: (argb >> 16) & 0xFF,
        green: (argb >> 8) & 0xFF,
        blue: argb & 0xFF,
        a: (argb >> 24) & 0xFF
    )
}

Called as

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF, a: 0xFF)
let color2 = UIColor(argb: 0xFFFFFFFF)

Or a combination of the previous methods. There is absolutely no need to use strings.

---

Related Topics