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Generate a random color (UIColor) in Objective-C
/*
Distributed under The MIT License:
http://opensource.org/licenses/mit-license.php
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
CGFloat hue = ( arc4random() % 256 / 256.0 ); // 0.0 to 1.0
CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from white
CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from black
UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];

Thanks!

Awesome, thanks.

thank you so much for this.

pixind commented Mar 20, 2013

Thanks a lot!

thanks you for your share

thanks you :D

joslinm commented Jul 1, 2013

thank you this is great for debugging. i set background color to random color when laying out many subviews

Thank you!

Thanks! its great for debugging.

Quite a snippet there :)

Thx a lot for ur share~

Great, thanks

Great 1 ! Thx

Thanks man :)

Awesome :)

YOwatari commented Dec 6, 2013

Awesome!

Thanks!

Thanks!

sleroux commented Feb 13, 2014

Thanks!

Thanks!

Thanks!

0oneo commented Mar 12, 2014

thanks!!!

Thanx, this is a great solution! :)

guarani commented May 17, 2014

Cheers!

jwyjoy commented May 27, 2014

Thanks!

Boom, what I needed, thanks.

Thanks!

Thanks!

short and sweet. thanks for saving me some time!

Great!
Thnks

Thank you!

woo hoo :)))) Thank you very much :)

ho hooo

Thanks

r00m commented Jan 16, 2015

Thanks! This is great for debugging!

thanks so much!

Obrigado

vguerra commented Mar 20, 2015

Thank you for the snippet @kylefox ... I think that on line #26 one should divide by 255 .. mod 256 yields a number between 0 and 255 otherwise you'll never get to 1.0.

sapjjr commented Mar 22, 2015

Mine was a bit more long but it work

func changeBackgroundColor() {
// this has been taken from stackoverflow.com/questions/27390234/changing-main-view-controller-background-color-from-value-in-nsuserdefaults
//which gave me idea on how the background color works
// initialise defaults
let defaults = NSUserDefaults.standardUserDefaults()
// Start color off with a default value
var color = UIColor.grayColor()
var backcolor = 0

    if let backColor = defaults.objectForKey("backColor") as? String {
        // accessing the variable
        switch backColor {
        case "1": color = UIColor.redColor()
        case "2": color = UIColor.greenColor()
        case "3": color = UIColor.cyanColor()
        case "4": color = UIColor.yellowColor()
        case "5": color = UIColor.grayColor()
        case "6": color = UIColor.orangeColor()
        default: break




        }
    }

    //this has been lifted from :
    //stackoverflow.com/questions/24007129/how-does-one-generate-a-random-number-in-apples-swift-language
    //to give ideas on how random numbers work
    // and also cast from Int to String via
    //  stackoverflow.com/questions/24161336/convert-int-to-string-in-swift
    //to give ideas on how random numbers work


    NSUserDefaults.standardUserDefaults().setObject( "\(String (Int(arc4random_uniform(UInt32(6)+1))))", forKey: "backColor") //saving a random number and calling it backcolor
    NSUserDefaults.standardUserDefaults().synchronize() //
    view.backgroundColor = color

}
@ghost

ghost commented Apr 6, 2015

Beauty!

colasbd commented Apr 30, 2015

Thanks !

Here is the snippet 
CGFloat redLevel    = rand() / (float) RAND_MAX;
CGFloat greenLevel  = rand() / (float) RAND_MAX;
CGFloat blueLevel   = rand() / (float) RAND_MAX;

self.view.backgroundColor = [UIColor colorWithRed: redLevel
                                            green: greenLevel
                                             blue: blueLevel
                                            alpha: 1.0];

Thank you very much!

Pastez commented Jun 24, 2015

Thanks

Swift:

    let hue = CGFloat(Double(arc4random() % 256) / 256.0) // 0.0 to 1.0
    let saturation = CGFloat(Double(arc4random() % 128) / 266.0 + 0.5) // 0.5 to 1.0, away from white
    let brightness = CGFloat(Double(arc4random() % 128) / 256.0 + 0.5) // 0.5 to 1.0, away from black
    return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1.0)

Thanks!

ardarda commented Aug 4, 2015

Thx!

Nice, thank you!

domagojb commented Sep 1, 2015

Nice thanks

Thanks a lot

I have a color code like "15233421". How can I consider alpha value while using any of the solution?

SudoKel commented Feb 19, 2017

Thank you! 👍

Thank you so much for this share. It helps people like me who are new to iOS programming in ObjC

Great...!

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