Swift:Type String的值永远不能为nil,不允许比较

Question

这是我的代码

func enteredByStr(S:String) -> String? {
    var healthactionplan : MyHealthActionPlanCondition

    if healthactionplan.addedBy != nil  {
        healthactionplan.addedBy = "System"
    } else {
        healthactionplan.addedBy = "Member"
    }
}

我甚至都遵循这个这个和这个.但仍然无法解决.任何人都可以解释为什么???

Answer 1

Type String的值永远不能为nil,不允许比较

错误消息显示您的一切

addedBy是一个String.所以检查isEmptyaddedBy

 if healthactionplan.addedBy.isEmpty   {
    healthactionplan.addedBy = "System"
} else {
    healthactionplan.addedBy = "Member"
}