进入iOS模拟器菜单，选择“重置内容和设置”。

或者，您可以退出并重新打开模拟器。

这个问题在Xcode 6发布说明中有讨论

在iOS模拟器上测试可能会产生错误，指示 应用程序无法安装或启动。重新运行测试或 开始另一个集成。(17733855)

我在苹果开发者论坛iOS模拟器调试的帖子中也有讨论

"(Domain = FBSOpenApplicationErrorDomain, Code = 4)", "(Domain NSPOSIXErrorDomain, Code = 3"), "Domain=IDEUnitTestsOperationsObserverErrorDomain Code=3", "Lost Connection to ...", "Debugger disconnected", or app getting SIGKILLed soon after launch Upon installation of an app, SpringBoard will SIGKILL that app's process in order to force a relaunch of the app with the new executable. The problem is that there is a race condition whereby SpringBoard may accidentally SIGKILL a new process that we just launched rather than the old process. Which of the various error messages you get depends on exactly when in the launch process the SIGKILL was delivered. Normally, this shouldn't happen, so the advise is to just try again (sorry =/). If you find that this happes to you all the time or more frequently than you can tollerate, we are incredibly sorry. We are aware that systems with slower disk I/O will see this happen more frequently than faster systems, so if you are using an NFS home directory, you may want to create a local directory for your simulator data and setup a simlink to it from ~/Library/Developer/CoreSimulator

注意，最初的问题是关于域fbssystemservicdomain，而我在devforums上的帖子提到了FBSOpenApplicationErrorDomain。fbssystemservicdomain在早期版本的iOS 8.0 beta中使用。

没有一个解决方案对我有效，包括“重置内容和设置”这个公认的答案。

我能够让它运行的唯一方法是下载之前的iOS模拟器版本，让我可以安装应用程序。

进入iOS模拟器菜单，选择“重置内容和设置”。

或者，您可以退出并重新打开模拟器。

退出并重新打开模拟器就足够了，这已经在Xcode 6.0.1版本中得到了验证。

我建议你使用Xcode 6.1的稳定版本。

FBSOpenApplicationErrorDomain, code =4 error suggests it is an error from 
cached data on the simulator.

有三种可能的解决方案:

干净的模拟器。使用(Command + Shift + k)作为快捷键或转到Product ->清洁 退出模拟器并重新启动它。 打开模拟器。选择iOS模拟器->重置内容和设置…