小编Car*_*kis的帖子

我有一个这样的代码（在操场上玩：

protocol ServiceProtocol {
    var enabled: Bool { get set }
}

class Service: ServiceProtocol {
    var enabled: Bool = false
}

class A {
    let service = Service()
}

class B {
    let service: ServiceProtocol = Service()
}

let a = A()
let b = B()

a.service.enabled = false
b.service.enabled = false // <-- the error is here: Cannot assign to property: 'service' is a 'let' constant

如果我引用service为Service(class A)，则一切都按预期进行。在 class 中B，service …