s := os.Getenv(envvar)
	if s == "" {
		log.Fatalf("%s not set\nrun $GOROOT/misc/ios/detect.go to attempt to autodetect", envvar)
	}
	return s
}

func assembleApp(appdir, bin string) error {
	if err := os.MkdirAll(appdir, 0755); err != nil {
		return err
	}

	if err := cp(filepath.Join(appdir, "gotest"), bin); err != nil {
		return err
	}

	pkgpath, err := copyLocalData(appdir)
	if err != nil {