Ex :
<attr name="myProperty" format="enum">
<enum name="None" value="0"/>
<enum name="One" value="1"/>
<enum name="Two" value="2"/>
<enum name="Three" value="3"/>
</attr>
Use like this:
<YourCustomView
...
app:myProperty="One"/>
Reference
https://stackoverflow.com/a/15231645/1329126