How do I check if a string contains another string in Swift?

Question

In Objective-C the code to check for a substring in an NSString is:

NSString *string = @"hello Swift"; NSRange textRange =[string rangeOfString:@"Swift"]; if(textRange.location != NSNotFound) {     NSLog(@"exists"); } 

But how do I do this in Swift?

Answer 1

You can do exactly the same call with Swift:

Swift 4 & Swift 5

In Swift 4 String is a collection of Character values, it wasn't like this in Swift 2 and 3, so you can use this more concise code¹:

let string = "hello Swift" if string.contains("Swift") {     print("exists") } 

Swift 3.0+

var string = "hello Swift"  if string.range(of:"Swift") != nil {      print("exists") }  // alternative: not case sensitive if string.lowercased().range(of:"swift") != nil {     print("exists") } 

Older Swift

var string = "hello Swift"  if string.rangeOfString("Swift") != nil{      println("exists") }  // alternative: not case sensitive if string.lowercaseString.rangeOfString("swift") != nil {     println("exists") } 

I hope this is a helpful solution since some people, including me, encountered some strange problems by calling containsString().¹

PS. Don't forget to import Foundation

Footnotes

1. Just remember that using collection functions on Strings has some edge cases which can give you unexpected results, e. g. when dealing with emojis or other grapheme clusters like accented letters.

Answer 2

Extension way

Swift 4

extension String {     func contains(find: String) -> Bool{         return self.range(of: find) != nil     }     func containsIgnoringCase(find: String) -> Bool{         return self.range(of: find, options: .caseInsensitive) != nil     } }  var value = "Hello world"  print(value.contains("Hello")) // true print(value.contains("bo"))    // false  print(value.containsIgnoringCase(find: "hello"))    // true print(value.containsIgnoringCase(find: "Hello"))    // true print(value.containsIgnoringCase(find: "bo"))       // false 

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Generally Swift 4 has contains method however it available from iOS 8.0+

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Swift 3.1

You can write extension contains: and containsIgnoringCase for String

extension String {      func contains(_ find: String) -> Bool{      return self.range(of: find) != nil    }     func containsIgnoringCase(_ find: String) -> Bool{      return self.range(of: find, options: .caseInsensitive) != nil     }  } 

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Older Swift version

extension String {      func contains(find: String) -> Bool{        return self.rangeOfString(find) != nil      }      func containsIgnoringCase(find: String) -> Bool{        return self.rangeOfString(find, options: NSStringCompareOptions.CaseInsensitiveSearch) != nil      } } 

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Example:

var value = "Hello world"  print(value.contains("Hello")) // true print(value.contains("bo"))    // false  print(value.containsIgnoringCase("hello"))    // true print(value.containsIgnoringCase("Hello"))    // true print(value.containsIgnoringCase("bo"))       // false