iOS simulator运行程序出现问题：
An error was encountered while running (Domain = FBSOpenApplicationErrorDomain, Code = 4)
解决方案：（重启模拟器）
iOS Simulator----> Reset Contents and Settings ----> Reset
An error was encountered while running (Domain = FBSOpenApplicationErrorDomain, Code = 4)
原文：http://www.cnblogs.com/Jianpusen/p/4298399.html