如何在 Swift 中使用关联值检查枚举的枚举大小写

Question

我正在尝试检查每个案例都有关联值的枚举的案例，如下所示：

enum status {
    case awake(obj1)
    case sleeping(obj2)
    case walking(obj3)
    case running(obj4)
}

我正在使用if(status == deviceStatus.awake){ 检查状态情况并收到错误：Binary operator '==' cannot be applied to operands of type 'status' and '(obj1) -> status'

Answer 1

您可以使用if case .awake = deviceStatus 来检查deviceStatus 是否设置为awake 枚举值：

class Obj1 { }
class Obj2 { }
class Obj3 { }
class Obj4 { }

enum Status {
    case awake(Obj1)
    case sleeping(Obj2)
    case walking(Obj3)
    case running(Obj4)
}

let deviceStatus = Status.awake(Obj1())

if case .awake = deviceStatus {
    print("awake")
} else if case .sleeping = deviceStatus {
    print("sleeping")
}

// you can also use a switch statement

switch deviceStatus {
case .awake:
    print("awake")
case .sleeping:
    print("sleeping")
default:
    print("something else")
}