Pass data from callback to React component?

I'm rendering a react component that needs data that returns asynchronously. How should I pass this to the react component when it returns from the callback?

currently in render function:

var dataToReturn; 
asynchCall(args, function(err, results) {
  dataToReturn = results;
})

return (
    <MyComponent data={dataToReturn} />
)

This of course is not working out because the data has not returned yet. If I move the render into the callback, that seems like a bad programming pattern. Is there anything in the React API meant for this use case?

thank you!