If you want to set backgroundColor of button programmatically then this code will surly help you
Swift 3 and Swift 4
self.yourButton.backgroundColor = UIColor.red
Swift 2.3 or lower
self.yourButton.backgroundColor = UIColor.redColor()
Using RGB
self.yourButton.backgroundColor = UIColor(red: 102/255, green: 250/255, blue: 51/255, alpha: 0.5)
or you can use float values
button.backgroundColor = UIColor(red: 0.4, green: 1.0, blue: 0.2, alpha: 0.5)