Swift filter array of objects

Question

class book{     var nameOfBook: String! }  var englishBooks=[book(),book(),book()] var arr = englishBooks.filter {     contains($0.nameOfBook, "rt") } 

I'm using this filter but with error cannot invoke filter with an argument

Answer 1

contains() checks if a sequence contains a given element, e.g. if a String contains a given Character.

If your intention is to find all books where the name contains the substring "rt", then you can use rangeOfString():

var arr = englishBooks.filter {     $0.nameOfBook.rangeOfString("rt") != nil } 

or for case-insensitive comparison:

var arr = englishBooks.filter {     $0.nameOfBook.rangeOfString("rt", options: .CaseInsensitiveSearch) != nil } 

As of Swift 2, you can use

nameOfBook.containsString("rt") // or nameOfBook.localizedCaseInsensitiveContainsString("rt") 

and in Swift 3 this is

nameOfBook.contains("rt") // or nameOfBook.localizedStandardContains("rt") // or nameOfBook.range(of: "rt", options: .caseInsensitive) != nil 

Answer 2

Sorry this is an old thread. Change you code slightly to properly init your variable 'nameOfBook'.

class book{    var nameOfBook: String!    init(name: String) {       nameOfBook = name    } } 

Then we can create an array of books.

var englishBooks = [book(name: "Big Nose"), book(name: "English Future  Prime Minister"), book(name: "Phenomenon")] 

The array's 'filter' function takes one argument and some logics, 'contains' function can take a simplest form of a string you are searching for.

let list1 = englishBooks.filter { (name) -> Bool in    name.contains("English") } 

You can then print out list1 like so:

let list2 = arr1.map({ (book) -> String in    return book.nameOfBook }) print(list2)  // print ["English Future Prime Minister"] 

Above two snippets can be written short hand like so:

let list3 = englishBooks.filter{ ($0.nameOfBook.contains("English")) } print(list3.map({"\($0.nameOfBook!)"}))