This bundle patches the Cocoa Text System to add a Vi-like command mode. After entering command-mode (typically, by hitting escape in Vi), ordinary Vi commands can be typed and the text field will be updated accordingly. Essentially, this add Vi command functionality (albeit a small subset) to any (and all) text editors that use the Cocoa text system; e.g., Safari, TeXShop, XCode, etc. Note, however, this does not work for other programs that do not use the Cocoa system.
All the text windows, will initialize in "input" mode (standard cocoa text input). You invoke the Vi-command window (exit the input mode) by hitting ` (the back-apostrophe key, this is customizable, see installation instructions) and then key in your favorite Vi commands. For example, move down a line 'j', move right 'l', delete two lines 'd2d', and so on. You enter back into "input" mode by typing the 'i'. You get the idea. Right now, you should be thinking -- "you mean the editor in XCode will behave like Vi?" Answer: Yes.