IOS UIAUTOMATION - How to capturescreen and finish script when the test-app suspended

I got a problem about ios uiautomation. When the instruments runs(CIL), tap the button in test-app. The app will be suspended and change to other app(like appstore).So the instruments also will be suspended. Now I want to capture the screen (other app) in automation script, but it is suspended.So how to do it and finished the script? Thanks!