I know ios apps have the following lifecycle. active background suspended not running inactive My question is if my app can be killed in background state in the lifecycle above? Especially, I'm using beginBackgroundTask(expirationHandler:) to extend background time before suspended. Then my app is terminated with the following message without expirationHandler being called. Message from debugger: Terminated due to signal 9 Does this potentially happen? Actually I'm runnning a heavy task that requires CPU usage in background state, so is this a cause of this problem?