重新启动应用程序时获取异常SIGKILL

I build and run a project in iPhone simulator. I send it to background by pressing the home button. Then I double press the home button to find my app in the background and tap it. It becomes active and the app continues to run. Here I got no problem no matter how many times I repeat this. Then I kill the process by tapping the little red minus sign on the app's icon. But if I again tap the app icon to relaunch it I get SIGKILL error and app crashes. What could be the reason for this? Could it be caused by my XCode preferences?I build and run a project in iPhone simulator.