arrays - Swift 2.0 过滤自定义对象数组 - 无法使用列表类型的参数调用 'filter'

Question

尝试过滤继承自 NSObject 的自定义对象类型 ParseEmployee 的数组。

知道是什么导致了这个错误吗？

Answer 1

考虑以下示例:

struct MyEmployee {
    var employeeId : Int
    var employeeName : String
    var employeeAge : Int
    var employeeGender : String

    init(_ id: Int, _ name: String, _ age: Int, _ gender: String) {
        employeeId = id
        employeeName = name
        employeeAge = age
        employeeGender = gender
    }
}

var arrayOfEmployees : [MyEmployee] = [MyEmployee(1, "John", 28, "Male"), MyEmployee(2, "Sarah", 35, "Female"), MyEmployee(3, "Christine", 24, "Female")]

var filtered = arrayOfEmployees.filter {employee in employee.employeeAge < 30 }
print(filtered) // Employee objects John and Christine

在.filter之后关闭数组的后缀必须是返回类型 Bool ("element-type-of-array" -> Bool)。您要么显式添加 return或者简单地确保 employee in 之后的声明是一个评估类型 Bool (例如 employee.employeeAge < 30 ，返回 true 或 false )。

请注意，您可以将闭包视为任何匿名闭包类型，不一定使用单行语句。例如:

var anotherFiltered = arrayOfEmployees.filter{
    employee in
    return employee.employeeAge < 30 && employee.employeeGender == "Female" }
print(anotherFiltered) // Employee object Christine