# ~=(_:_:) Returns a Boolean value indicating whether two arguments match by value equality. ``` func ~= (a: T, b: T) -> Bool where T : Equatable ``` ## Parameters `a` A value to compare. `b` Another value to compare. ## Discussion The pattern-matching operator (`~=`) is used internally in `case` statements for pattern matching. When you match against an `Equatable` value in a `case` statement, this operator is called behind the scenes. ``` let weekday = 3 let lunch: String switch weekday { case 3: lunch = "Taco Tuesday!" default: lunch = "Pizza again." } // lunch == "Taco Tuesday!" ``` In this example, the `case 3` expression uses this pattern-matching operator to test whether `weekday` is equal to the value `3`. > Note: In most cases, you should use the equal-to operator (`==`) to test > whether two instances are equal. The pattern-matching operator is > primarily intended to enable `case` statement pattern matching. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)