无法为ios和android添加平台(错误：ENOENT,没有这样的文件或目录)

我试图开始使用mac OSX上的离子演示
http://ionicframework.com/docs/guide/installation.html

我到了应该添加平台的地步,所以我在终端输入了这个命令：

ionic platform add android

但后来我遇到了这些错误：

Error: ENOENT, no such file or directory '/Users/adeyo/todo/ionic-app-base-master/plugins/android.json'
at Error (native)
at Object.fs.openSync (fs.js:455:18)
at Object.fs.writeFileSync (fs.js:1001:15)
at Object.save_platform_json (/usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/util/config-changes.js:476:8)
at Platformmunger_process [as process] (/usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/util/config-changes.js:401:13)
at Object.exports.process (/usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/util/config-changes.js:80:12)
at Object.handlePrepare (/usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/prepare.js:72:20)
at /usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/prepare.js:102:25
at Array.map (native)
at /usr/local/etc/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/prepare.js:66:40

当我尝试添加ios平台时出现类似的错误,我不知道如何解决这个问题.

解决方法:

创建文件夹加上安装ant对我有用：

mkdir plugins
brew install ant