比较Swift中对象的两个实例

Question

给定以下类,如何将两个实例中的所有值相互比较？

// Client Object
//
class PLClient {
    var name = String()
    var id = String()
    var email = String()
    var mobile = String()
    var companyId = String()
    var companyName = String()

    convenience init (copyFrom: PLClient) {
        self.init()
        self.name =  copyFrom.name
        self.email = copyFrom.email
        self.mobile = copyFrom.mobile
        self.companyId = copyFrom.companyId
        self.companyName = copyFrom.companyName

    }

}

var clientOne = PLClient()

var clientTwo = PLClient(copyFrom: clientOne)

if clientOne == clientTwo {   // Binary operator "==" cannot be applied to two PLClient operands
    println("No changes made")
} else {
    println("Changes made. Updating server.")
}

用例是在一个从服务器提供数据的应用程序中.将数据转换为对象后,将生成对象的副本.用户能够编辑各种字段等,这些字段会更改其中一个对象中的值.

可能已更新的主要对象需要与该对象的副本进行比较.如果对象相等(所有属性的值相同),则没有任何反应.如果任何值不相等,则应用程序将更改提交给服务器.

如代码示例所示,==不接受运算符,因为未指定值.使用===不会达到预期的结果,因为它们总是两个独立的实例.

Answer 1

指示您的类符合Equatable协议,然后实现==运算符.

像这样的东西:

class PLClient: Equatable 
{
    var name = String()
    var id = String()
    var email = String()
    var mobile = String()
    var companyId = String()
    var companyName = String()
    //The rest of your class code goes here

    public static func ==(lhs: PLClient, rhs: PLClient) -> Bool{
        return 
            lhs.name == rhs.name &&
            lhs.id == rhs.id &&
            lhs.email == rhs.email &&
            lhs.mobile == rhs.mobile &&
            lhs.companyId == rhs.companyId &&
            lhs.companyName == rhs.companyName
    }
}

Answer 2

根据Duncan C的回答,我提出了一个替代方案,它更加清晰,以自定义方式使用:

// Client Object
//
class PLClient {
    var name = String()
    var id = String()
    var email = String()
    var mobile = String()
    var companyId = String()
    var companyName = String()

    convenience init (copyFrom: PLClient) {
        self.init()
        self.name = copyFrom.name
        self.email = copyFrom.email
        self.mobile = copyFrom.mobile
        self.companyId = copyFrom.companyId
        self.companyName = copyFrom.companyName   
    }

    func equals (compareTo:PLClient) -> Bool {
        return
            self.name == compareTo.name &&
            self.email == compareTo.email &&
            self.mobile == compareTo.mobile
    }

}

var clientOne = PLClient()
var clientTwo = PLClient(copyFrom: clientOne)

if clientOne.equals(clientTwo) {
    println("No changes made")
} else {
    println("Changes made. Updating server.")
}