# Assertions A common way of highlighting unexpected behaviors in Swift is by using [assertions](https://developer.apple.com/documentation/swift/1541112-assert). Inside the Stream SDKs, we use wrappers around it (`log.assert`/`log.assertionFailure`). This is because we want to allow the integrators to silence those if they want to. You can change that behavior by changing the value for `assertionsEnabled` as follows: ```swift StreamRuntimeCheck.assertionsEnabled = true ``` The default value for this property is `false` Independently of the value of this flag, a message will always be printed in the console. When enabling Stream assertions, the default behavior of assertions still apply: - In playgrounds and -Onone builds (the default for Xcode’s Debug configuration): If the condition evaluates to false, stop program execution in a state ready for the debugger after printing the message. - In -O builds (the default for Xcode’s Release configuration), the condition is not evaluated, and there are no effects. - In -Ounchecked builds, the condition is not evaluated, but the optimizer may assume that it always evaluates to true. Failure to satisfy that assumption is a serious programming error. Read more [here](https://developer.apple.com/documentation/swift/1541112-assert). --- This page was last updated at 2026-04-17T17:33:38.737Z. For the most recent version of this documentation, visit [https://getstream.io/chat/docs/sdk/ios/v4/advanced/assertions/](https://getstream.io/chat/docs/sdk/ios/v4/advanced/assertions/).