---
title: XCTDarwinNotificationExpectation.Handler
framework: xctest
role: symbol
role_heading: Type Alias
path: xctest/xctdarwinnotificationexpectation/handler-swift.typealias
---

# XCTDarwinNotificationExpectation.Handler

A custom handler to be called when a matching notification is received.

## Declaration

```swift
typealias Handler = @Sendable () -> Bool
```

## Return Value

Return Value Your custom handler should return true if the expectation is considered fulfilled after the notification is received, otherwise false.

## See Also

### Custom Notification Evaluation

- [handler](xctest/xctdarwinnotificationexpectation/handler-swift.property.md)