元运算符“ - ”不能应用于类型的操作数“@lvalue INT”

Question

@IBAction func blueBtnAct(_ sender: AnyObject) { 
    score++ //error bcause Unary operator '++' cannot be applied to an operand of type '@lvalue Int' 
    blueLbl.text = "\(score)" 
    GrenLbl.text = "\(score)" 
    testScore() 
} 
@IBAction func GrenBtnAct(_ sender: AnyObject) { 
    score-- //error bcause Unary operator '--' cannot be applied to an operand of type '@lvalue Int' 
    blueLbl.text = "\(score)" 
    GrenLbl.text = "\(score)" 
    testScore() 
} 

Answer 1

您应该使用的，而不是score++