如何使用Swift 3插入具有可选参数的Sqlite [英] How to insert into Sqlite with optional parameters using Swift 3

问题描述

我的此类带有一些可选属性:

I have this class with some optional properties:

class Address {
    var Id: Int64
    var AddressType: Int64
    var AddressStatus: Int64
    var Address1: String?
    var Address2: String?
    var City: String?
    var State: String?
    var Zip: String?
    var Country: String?
    var Latitude: Double?
    var Longitude: Double?
}

我正在尝试插入Sqlite数据库，如下所示:

I am trying to insert into a Sqlite database, like this:

let insert = table.insert(or: .replace, Id <- item.Id, AddressType <- item.AddressType, AddressStatus <- item.AddressStatus, Address1 <- item.Address1?, Address2 <- item.Address2?, City <- item.City?, State <- item.State?, Zip <- item.Zip?, Country <- item.Country?, Latitude <- item.Latitude?, Longitude <- item.Longitude?)

但是我得到这个构建错误:

But I get this build error:

Value of optional type 'String?' not unwrapped; did you mean to use '!' or '?'?

如果我使用'！'它会生成，但是运行时出现此错误:

If I use '!' it will build, but I get this error when I run:

unexpectedly found nil while unwrapping an Optional value

我还是Swift的新手，但据我所知，我不想使用'！'当值可以为零时，是正确的吗?

I am still new to Swift, but from what I know, I don't want to use '!' when the value can be nil, correct?

我不确定我在做什么错.

I'm not sure what I'm doing wrong here.

推荐答案

使所有类的属性常量(用let声明)，使其成为非可选的，并在所有Address属性参数中添加必需的init().顺便说一句，Swift约定以小写字母开始vars命名.注意:除非有要求，否则应使用Int而不是Int64.关于属性的可选性，您只需在初始化时为其指定默认值即可.顺便说一句，除非您需要使对象持久化(符合NSCoding)，否则最好使用结构:

Make all your class properties constants (declare with let) and make them non optional adding a required init() with all your Address properties parameters. BTW it is Swift convention to start your vars naming with a lowercase letter. Note: You should use Int instead of Int64 unless it is a requirement. Regarding the optionality of your properties you can just assign a default value for them at initialization time. Btw It is better to use a struct unless you need to make your object persist (NSCoding compliant):

struct Address {
    let id: Int
    let addressType: Int
    let addressStatus: Int
    let address1: String
    let address2: String
    let city: String
    let state: String
    let zip: String
    let country: String
    let latitude: Double?
    let longitude: Double?
    init(id: Int, addressType: Int, addressStatus: Int, address1: String = "", address2: String = "", city: String = "", state: String = "", zip: String = "", country: String = "", latitude: Double = nil, longitude: Double = nil) {
        self.id = id
        self.addressType = addressStatus
        self.addressStatus = addressStatus
        self.address1 = address1
        self.address2 = address2
        self.city = city
        self.state = state
        self.zip = zip
        self.country = country
        self.latitude = latitude
        self.longitude = longitude
    }
}

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因此，您可以按照以下步骤创建新对象地址:

---

So you can create your new object Address as follow:

let address1 = Address(id: 1, addressType: 2, addressStatus: 3)
let address2 = Address(id: 2, addressType: 3, addressStatus: 4, address1: "Any Address", latitude: 22.0, longitude: 43.0)   // You don't need to add all parameters as long as you keep them in the same order as your initializer

address2.latitude   // 22.0

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