How to show line number?
编辑时碰到的问题，想要看到line number
Xcode -> preference -> Text EditingHow to add relative-path file to product directory?
给OpenGL-first-program添加shader时碰到的问题，无法读取.vert, .frag
考虑如下情况：
FILE file = fopen("file.txt", "rb");
此处file.txt不在product directory下，直接run会出现no such file
解决方法：Build Phases -> Copy Files -> Destination -> Product Directory 然后用 + 添加文件
Note: clear Subpath field, disable Copy only when installing
