Swift filter array of objects

Question

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