add icu data to the library directly (ios)

engine/README.md

 cd $FLUTTER_ROOT
 ./flutter/tools/gn --unoptimized --ios            //disable bitcode
 ./flutter/tools/gn --unoptimized --ios --bitcode  //enable bitcode
+```
+
+add this line to the end of out/ios_debug_unopt/args.gn:
+```
+icu_use_data_file=false
+```
+
+finally run ninja:
+```
 ninja -C out/ios_debug_unopt/ flutter/third_party/txt:txt_lib
 ```
 
-
-### Prepare icu data (TODO: try to build it into the library directly!)
-
-move the built icu data file from $FLUTTER_ROOT/out/ios_debug_unopt/icudtl.dat to the StreamingAssets path
 
 
 ### Creat symbolic

engine/src/shell/platform/unity/darwin/ios/uiwidgets_panel.mm

   args.struct_size = sizeof(UIWidgetsProjectArgs);
   args.assets_path = streaming_assets_path;
   args.font_asset = settings;
-  //TODO: not support icu yet
-  
-  std::string icu_path = std::string(streaming_assets_path) + "/icudtl.dat";
-  args.icu_data_path = icu_path.c_str();
   
   args.command_line_argc = 0;
   args.command_line_argv = nullptr;