filteredArrayUsingPredicate does not exist in swift Array

Question

I have "UserDetails" struct objects in array..I want to filter the objects from array. But there is no option for "filteredArrayUsingPredicate" in Swift array.

My array creation

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

my userdetails code is

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

my code to create objects

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

Now I want to filter arrayOfUsers which one has userID "1".

so cant i filter with beta version? i am new to iOS,please make me correct if i did anything wrong.. — Mani murugan, Jun 24 '14 at 09:12
@Manimurugan nicael's point was that you have agreed to not discuss Apple's betas in public. I am not sure if this is applicable here, though, because Swift book and library reference are released to the public with no strings attached. — Sergey Kalinichenko, Jun 24 '14 at 09:16

Nate Cook · Accepted Answer · 2014-06-24T09:35:39.040

125

Swift arrays have a .filter method that takes a closure -- this will do it:

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

Closures can be simplified in a variety of ways. The full declaration of the closure would look more like this:

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

The difference between the two is that the first is using trailing closure syntax, shorthand argument names, type inference, and implicit return. You can read more about closures in Apple's Swift documentation.

edited Jun 24 '14 at 09:35

answered Jun 24 '14 at 09:16

Nate Cook

92,417
32
217
178

can you please tell me about $ symbol..what is the use of this ? – Mani murugan Jun 24 '14 at 09:25
2

`$0` is a shorthand argument name. I'll add a bit more detail. – Nate Cook Jun 24 '14 at 09:32
if it is array of dictionaries,then how can i implement predicate to filter data for userID == 1(if user id is the key of Dictionary) ? – Mani murugan Jun 24 '14 at 10:05
That's a little trickier, since subscripting a dictionary returns an Optional. You'd want to get the value from the dictionary, make sure it exists, then see if it's "1" and return true, false otherwise. – Nate Cook Jun 24 '14 at 10:16
1

@Manimurugan refer my answer – karthikPrabhu Alagu Jun 24 '14 at 13:25
i am using swift 1.2, it doesnt have method named `filter`, instead it have `filteredArrayUsingPredicate` method, but not working properly – Mehul Thakkar Jul 20 '15 at 09:16
Prettiest solution so far! Swift syntax is so light and convenient, thx Nate – Tib Jul 15 '16 at 08:17
2

NSPredicate vs Pure Swift filter, which is a better (faster, scalable ) solution ? – Cristian Cardoso Jan 24 '18 at 01:17

karthikPrabhu Alagu · Answer 2 · 2015-06-01T06:36:21.140

you can also use 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)");

//struct filtering

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)");
}

@karthik Prabhu What would you do if you have an array of structs rather than an array of dictionaries? `let filteredArray = arrNames.filter { namePredicate.evaluateWithObject($0) };` That line is giving me the error "Type 'myStruct' does not conform to protocol 'AnyObject'" — Hobsie, Jul 31 '14 at 19:47
I like your solution more because NSPredicates are way more powerful than simple string comparisons. Only the possibility to compare case insensitive in an easy way: `let predicate = NSPredicate(format: "description contains[c] %@", argumentArray: [searchText])` — blackjacx, Dec 05 '14 at 14:36
awesome! Was looking for this. This is really helpful when you're doing a ObjectiveC to swift conversion and don't really want to touch the predicate logic. — Vinayak, Jul 03 '20 at 12:22

score 5 · Answer 3 · answered Dec 17 '14 at 21:59

If you are filtering a dictionary you can do it like this.

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

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

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

Well the same applies to structs where you would filter its property

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
})

You can refer to this articles for more info. Filtering a Swift Array of Dictionaries or Object property

score 2 · Answer 4 · answered Jan 17 '18 at 07:34

In swift 3 or 4 you can use NSPredicate With Array

let pred : NSPredicate = NSPredicate(format: "points_status = %@", "0")
let   approvalRequestArray =  approvalRequestOriginalArray.filtered(using: pred) as NSArray


let provincesStartingWithM = NSPredicate(format: "name contains [cd] 'a'")

provinces.filtered(using: provincesStartingWithM)

For More information, You can Visit this link GitHub

score 2 · Answer 5 · answered May 02 '18 at 04:02

As it turns out, you don't have to compare only one filter at a time. You can apply logical conditionals to broaden the scope of the predicate. For example:

var foundArray = tempArray.filter{ String(describing:$0.id) .contains(searchText) || 
$0.name .contains(searchText) || $0.summary! .contains(searchText) || 
String(describing: $0.airDate).contains(searchText) || String(describing: $0.airTime).contains(searchText) || 
String(describing: $0.runTime).contains(searchText)}

works like a champ.

filteredArrayUsingPredicate does not exist in swift Array

5 Answers5

Linked