Xcode：消除警告“Umbrella header for m

https://stackoverflow.com/questions/31508434/xcode-llvm-7-0-disable-warning-umbrella-header-for-module-does-not-include-he

The warning flag is -Wincomplete-umbrella, so to suppress, pass -Wno-incomplete-umbrella

消除警告方法：

第一种：Build Settings - Other C Flags 添加 -Wno-incomplete-umbrella

第二种：在PCH预编译文件里添加 #pragma clang diagnostic ignored "-Wincomplete-umbrella"

要消除其他警告，可以先在这个网站查找对应的Flag，然后添加 #pragma clang diagnostic ignored "flag"