How to pull down the "submodel" resources

[masterchen]

I got an error say, cpp files missing while build the resource , then i checked the directory of the ios/calsses , the folder is empty .
info as follow :

from D:\OpenSource\github\Flutter\ecg_monitor\android\app
CMake Error at CMakeLists.txt:9 (add_library):
Cannot find source file:

  ../../ios/Classes/PanTompkinsQRS/src/panTompkins.cpp

Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm .h
.hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90 .f95 .f03 .hip .ispc 

[CCXXXI]

See: https://git-scm.com/book/en/v2/Git-Tools-Submodules
TL;DR: Add --recurse-submodules to git clone or run git submodule update --init --recursive after clone.