In an Android app developed with Appcelerator Titanium, calling .focus() on a textfield doesn’t always result in having the keyboard showing up. The Exygy ShowAndroidKeyboard Titanium module will force the keyboard to show up in any situation. Here is how to use it:

var k = require('com.exygy.showkeyboard');
k.showKeyboard();

The source code and the module are available on the Titanium marketplace or on Github.