tiny-events | tiny event system for Swift

Are you storing an observer in a local variable or constant instead of in a property? That's fine, but those warnings are hinting at something important, which is that the automatic reference counting system will consider unused local objects as being unnecessary and can destroy them immediately, and your closure won't get called if the observer is destroyed. The solution to this is to use the Swift standard library function withExtendedLifetime(_:_:) to tell the system explicitly that you want the observer to stay alive:. In my experience this doesn't come up frequently (if at all) in normal usage because it's unusual to have an event observer that is as short-lived as a function invocation, but this idiom is used extensively in the TinyEvent tests.