可以通过点击 Xcode6--解决问题>窗口 - >设备如下图所示：

Might be that resolve by tap Xcode6--> Window--> Device like following image:

当您选择设备选项时，您将打开以下窗口：

When you select Device Option you get following window open:

出现所有模拟器或连接设备。如果您发现没有模拟器，您可以通过单击 + 按钮添加，然后您将获得以下窗口创建模拟器。

There is appear all simulator or connected devices. If you found No simulator you can add by click on + Button then you get following window create simulator.

单击一个选项，有模拟器列表，你得到模拟器。希望能解决你的问题。

click an option there is simulator list and you get simulator. Hope that solve you issue.