swift Array中不存在filteredArrayUsingPredicate

Question

我在数组中有"UserDetails"结构对象.我想从数组中过滤对象.但是在Swift数组中没有"filteredArrayUsingPredicate"的选项.

我的阵列创建

var arrayOfUsers:UserDetails[] = UserDetails[]()

我的userdetails代码是

struct UserDetails{
    var userName:String
    var userID:String
    var userAge:String
    func userDescription()->String{
        return "name " + userName + "age " + userID
    }
}

我的代码来创建对象

        for a in 1...1000{
            var user:UserDetails = UserDetails(userName: "name", userID: String(a), userAge: "22")
            arrayOfUsers.append(user)
        }

现在我想过滤arrayOfUsers哪一个有userID"1".

Answer 1

Swift数组有一个.filter关闭的方法 - 这样做:

let filteredArray = arrayOfUsers.filter() { $0.userID == "1" }

可以通过多种方式简化闭包.关闭的完整声明看起来更像是这样的:

var filteredArray = arrayOfUsers.filter( { (user: UserDetails) -> Bool in
        return user.userID == "1"
    })

两者之间的区别在于第一个是使用尾随闭包语法,速记参数名称,类型推断和隐式返回.您可以在Apple的Swift文档中阅读有关闭包的更多信息.

Answer 2

你也可以使用NSPredicate

    var customerNameDict = ["firstName":"karthi","LastName":"alagu","MiddleName":"prabhu"];
    var clientNameDict = ["firstName":"Selva","LastName":"kumar","MiddleName":"m"];
    var employeeNameDict = ["firstName":"karthi","LastName":"prabhu","MiddleName":"kp"];
    var attributeValue = "karthi";

    var arrNames:Array = [customerNameDict,clientNameDict,employeeNameDict];


    var namePredicate =
        NSPredicate(format: "firstName like %@",attributeValue);

    let filteredArray = arrNames.filter { namePredicate.evaluateWithObject($0) };
    println("names = ,\(filteredArray)");

//结构过滤

struct myStruct
{
    var userid:String;
    var details:String;
    init() {
        userid = "default value";
        details = "default";
    }

};
var f1 = myStruct();
f1.userid = "1";
f1.details = "Good boy";

var f2 = myStruct();
f2.userid = "2";
f2.details = "Bad boy";
var arrNames1:Array = [f1,f2];
let filteredArrayStruct =  arrNames1.filter( { (user: myStruct) -> Bool in
    return user.userid == "1"
    })
println("filter array count = \(filteredArrayStruct.count)");
for  filteredValues in filteredArrayStruct
{
       println("filteredArrayStruct = ,\(filteredValues.details)");
}

Answer 3

如果您要过滤字典,可以这样做.

var visitors = [["age" : 22], ["age" : 41], ["age" : 23], ["age" : 30]]

var filteredVisitors = visitors.filter({
    $0["age"] < 30
})

println(filteredVisitors)
//[["age" : 22], ["age" : 23]]

这同样适用于过滤其属性的结构

struct Person {
    var age : Int?
    init(age: Int) {
        self.age = age
    }
}

var eventAttendees = [Person(age: 22), Person(age: 41), Person(age: 23), Person(age: 30)]

var filteredAttendees = eventAttendees.filter({
    $0.age < 30
})

您可以参考这篇文章了解更多信息.过滤字典或对象属性的Swift数组