React Native: How to split a file up into multiple files and import them?

In general you can do the following:

var MyClass = React.createClass({
    ...
)}

module.exports = MyClass;

This way you tell what should be publicly available.

And then, in your former big file you can load the contents like this:

var MyClass = require('./myclass.js');

Require returns the object that references the value of module.exports.

Here is the updated solution with using the import statement (in latest React-Native and generally Javascript adhering to ECMAScript6 and later):

file1 myClass.js:

export default class myClass {...}

file2 app.js:

import myClass from './myClass';

This is the basic version using a single default export. You can also export named exports that have to be explicitly listed on import. For more info see export and import.