Imperatively Change Route Title

[cancan101]

Provide a way to imperatively change the title shown in the ExNavigator for the current route.

[ide]

The way to do this is to implement renderTitle with a custom view that has an imperative method. There are several possible transitions for setting a title (e.g. cross-fading, sliding in, fading out then fading in) so ExNavigator lets you implement whatever behavior is right for your app.

[cancan101]

@ide how do I get a reference to the view returned by renderTitle?

[ide]

renderTitle={() => <View ref={c = { this._title = c; } />}

It's all standard React and JS all the way down.