macos auto build (very slow, but it works)

macos/flutter_libsparkmobile.podspec

@@ -18,6 +18,10 @@ A new Flutter project.
   # paths, so Classes contains a forwarder C file that relatively imports
   # `../src/*` so that the C sources can be shared among all target platforms.
   s.source           = { :path => '.' }
+  s.prepare_command = <<-CMD
+    # Add your build script here
+    "./run_build.sh"
+  CMD
   s.vendored_frameworks = 'flutter_libsparkmobile.framework'
   s.dependency 'FlutterMacOS'
 

macos/run_build.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+set -e
+cd ../scripts
+./prebuild.sh
+cd macos
+./build_all.sh