Question

我已对此进行了上下阅读，并在这里了解了基本知识-我只是不明白为什么会收到此错误。我使用第二个init从Firebase实例化一个客户，但是即使我注释掉其中的所有内容，我仍然会收到错误

Variable 'self.customerType' used before being initialized在初始化声明？

class Customer {

    enum customerTypes {
        case consumer
        case business
    }

    // MARK - properties

    var id: String?
    let customerType: customerTypes
    var name1: String
    var name2: String?
    var address: Address?
    var phone: String?
    var email: String?

    struct Address {
        var street: String
        var postalCode: String
        var city: String
        var country: String = "Norway"
    }

    init(type: customerTypes, name1: String, name2: String?, phone: String, email: String, address: Address? ) {
        self.customerType = type
        self.name1 = name1
        self.name2 = name2
        self.phone = phone
        self.email = email
        self.address = address
    }

     init?(data: [String: Any]) {

        guard let type = data["customerType"] as? String else { return }
        guard let name1 = data["name1"] as? String  else { return }

        self.customerType = type == "Consumer" ? .consumer : .business
        self.name1 = name1


//      if let name2 = data["name2"] as? String { self.name2 = name2 }
//      if let phone = data["phone"] as? String { self.phone = phone }
//      if let email = data["email"] as? String{ self.email = email }
//      if let address = data["address"] as? [String: Any] {
//          let street = address["street"] as? String
//          let postCode = address["postCode"] as? String
//          let city = address["city"] as? String
//          if street != nil && postCode != nil && city != nil {
//              self.address = Address(street: street!, postalCode: postCode!, city: city!)
//          }
//      }

    }

我在这里忽略了什么简单的问题？

Answer 1

您声明了一个初始化器，该初始化器承诺将返回初始化的const channel = client.channels.cache.get('<channelid>'); const person1 = client.users.cache.get('<userid>'); const person = client.users.cache.get('<userid>'); client.on('message', message =>{ client.on('presenceUpdate', () =>{ if(person1.user.presence.status === 'dnd' || person1.user.presence.status === 'online'){ channelforstatus.send('person1 is now online'); } else if(peron1.user.presence.status === 'offline' || person1.user.presence.status === 'idle'){ channel.send('person1 is offline'); } client.on('message', message => { client.on('presenceUpdate', () =>{ if(person.user.presence.status === 'dnd' || person.user.presence.status === 'online'){ channel.send('person is now on'); } else if(person.user.presence.status === 'offline' || person.user.presence.status === 'idle'){ channel.send('person is now off'); } }); }); }); });或不返回.send()（因为它容易出错）。您还声明Customer作为该类的属性之一。

这意味着，如果您成功从初始值设定项返回（也就是说，不返回Customer），则必须将该属性初始化为某个值。

该错误对于错误的位置不是很有帮助，因为该错误实际上在下面的行中。只需将let customerType: customerTypes放入nil中，就表示您的对象已成功初始化，但尚未成功初始化，因为尚未将return设置为值。

因此，如果将guard放在customerType子句中，您将说初始化失败，则无需在return nil中输入值。

Answer 2

没有初始值的属性需要在init内设置。您可以通过将其设置为Optional或设置默认值来解决此问题：

init?(data: [String: Any]) {
    customerType = .consumer
    name1 = ""
}

或：

var customerType: customerTypes?
var name1: String?

注意：通过设置属性Optional，编译器会假定初始值为nil。

失败的初始化-初始化之前使用的变量'self.customerType'

2 个答案: