filteredArrayUsingPredicate does not exist in swif

问题:

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".

回答1:

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.

回答2:

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)");
}

回答3:

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

回答4:

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

回答5:

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.