A problem occurred evaluating project ':app'. > SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable.

A problem occurred evaluating project ':app'.  

> SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable.

Go to the android/ directory of your project

Create a file called local.properties with this line:

sdk.dir = /Users/USERNAME/Library/Android/sdk