Xcode不在模拟器上运行应用程序。(应用程序意外退出)

I'm developing for iPad (iOS 7), using Xcode 5.0.2. Yesterday morning I was playing around with the app (my first app) and every time I ran it, it was displayed in the emulator perfectly. But after some 5/6 runs Xcode just stopped launching my app in the simulator. I started to receive this message:I'm developing for iPad (iOS 7), using Xcode 5.