安装AndroidStudio后，执行react-native run-android报如下：
SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable.
是因为ANDROID_HOME没有配置。
Mac下默认安装AndroidStudio后，sdk路径为cd ~/Library/Android/sdk/，需添加以下配置到 ~/.bash_profile：
export ANDROID_HOME=/Users/apple/Library/Android/sdk
export PATH=${PATH}:${ANDROID_HOME}/tools
export PATH=${PATH}:${ANDROID_HOME}/platform-tools
