## Swift 运算符之三元运算符 ``` question ? answer1 : answer2 ``` ### Demo 场景：当手机电量小于 20 的时候，显示红色，当大于 20 的时候显示绿色。 ``` import UIKit var battery = 18 var batterColor: UIColor if battery <= 20 { batterColor = UIColor.red } else { batterColor = UIColor.green } batterColor var batterColor2 = ( battery <= 20 ) ? UIColor.red : UIColor.green ```