Can not generate random color

Question

I want change color always when user tap on an element, but after tap I got white or transparent color (I don't see the object)

There is my code:

let red = arc4random_uniform(256)
let green = arc4random_uniform(256)
let blue = arc4random_uniform(256)
color = UIColor(red: CGFloat(red), green: CGFloat(green), blue: CGFloat(blue), alpha: CGFloat(1))

If I use UIColor.green or another color its works

I believe the arguments to `UIColor(red:, ...)` initializer should be in the range `[0.0, 1.0]`. — dfrib, Mar 13 '17 at 16:36
Did you read the documentation for `UIColor`? That initialiser takes values between 0.0 and 1.0, not 0 - 255. — Grimxn, Mar 13 '17 at 16:36
try http://stackoverflow.com/questions/29779128/how-to-make-a-random-background-color-with-swift — Ortensia C., Mar 13 '17 at 16:37
let red = arc4random_uniform(256) let green = arc4random_uniform(256) let blue = arc4random_uniform(256) let maxValue: Float = 255 let color = UIColor(red: CGFloat(Float(red)/maxValue), green: CGFloat(Float(green)/maxValue), blue: CGFloat(Float(blue)/maxValue), alpha: CGFloat(1)) — chinthakad, Mar 13 '17 at 16:55

score 2 · Accepted Answer · answered Mar 13 '17 at 16:38

2

RGB values have to be specified in the range of 0 to 1.0. Divide your RGB values by 256 since values above 1.0 are interpreted as 1.0. See https://developer.apple.com/reference/uikit/uicolor/1621925-init

answered Mar 13 '17 at 16:38

Kiran Dwarkan

56
4

score 0 · Answer 2 · answered Mar 13 '17 at 16:38

0

Try dividing each of the values by 1 before creating a colour:

color = UIColor(red: CGFloat(1.0 / red), green: CGFloat(1.0 / green), blue: CGFloat(1.0 / blue), alpha: CGFloat(1))

answered Mar 13 '17 at 16:38

Matthew Hallatt

1,310
12
24

score 0 · Answer 3 · answered Mar 13 '17 at 16:38

Try with this.

let red = randomInteger(limited: 256)
let green = randomInteger(limited: 256)
let blue = randomInteger(limited: 256)

color = UIColor(red: CGFloat(256 / red), green: CGFloat(256 / green), blue: CGFloat(256 / blue), alpha: CGFloat(1.0))

public func randomInteger(limited limit: Int) -> Int
{
    return Int(arc4random_uniform(UInt32(limit)))
}

But you have to do something with the returnes values. Color range is from 0.0 to 1.0

Can not generate random color

3 Answers3