Compiling IB documents for earlier than iOS 7 is no longer supported

最近在苹果官方网站下载了一个 Demo，由于年代久远，Xcode 打开编译后，直接提示如下错误信息：

Compiling IB documents for earlier than iOS 7 is no longer supported.

只需要打开对应的 Storyboard 文件，在右侧面板中把 File inspector - Interface Builder Document - Builds for 改成 iOS 7.0 and Later 即可。