Keyboard shortcuts in iOS?

Question

Is it possible to capture command-key sequences in 3rd party iPad/iPhone apps?

Long version:

On my excellent journey of discovery vis-a-vis my new iPad with it's gleaming keyboard dock, I discovered, much to my joy, that when editing text in standard issue text views; commands ranging from ⌘C/⌘P for copy-paste and ^A, ^B, ^E and friends for line and character jumping works.

So far so good, yeah? Problem is, this enthralling behaviour seems limited to text fields, and more specifically, standard issue text fields. What I would really like is to capture events like these for my own use.

An issue I often find with a lot of apps is that they tend to either be close to useless, or at least cumbersome, without the keyboard dock (e.g. the iWork Suite), or close to useless, or at least cumbersome, with the keyboard dock (most other applications that don't rely heavily on text input, but rather touch gestures [that is to say, most other applications period]).

Many games, for instance Civilization Revolutions, and similar, would benefit massively from just the simple addition of the ability to use the arrow keys to move units and the enter key to end turn.

So the question, then, as stated above: Is there a way to capture and respond to these events in order to offer an alternative to touch commands for those that desire this and have the hardware?

Disclaimer: I have no intention of developing applications that rely exclusively on keyboard input, of course, and nor should anyone else. The touch interface is paramount. It's just not always completely practical.

Answer 1

The only way (that I know of) to get input from the keyboard in iOS is using the UITextInput protocol. Unfortunately, the protocol doesn't give you the raw keys that were pressed, and instead sends you messages like "insert this string" and "move the caret to this position." So in order to know that an arrow key was pressed would require you to do some digging.

As for shortcuts with modifier keys, like copy/paste or undo/redo, Apple only seems to support the basics, and doesn't allow you to create custom ones. They use methods in UIResponder: –canPerformAction:withSender: and undoManager.

So if I were writing a game and wanted to take advantage of the keyboard I would subclass UIResponder and have it conform to the UITextInput protocol. And then make it the first responder. This however will probably bring up the software keyboard if a physical one is not present.

My own disclaimer: I haven't done all the hard work to use UITextInput in a way it wasn't meant to be used, so I don't know how feasible it would be to actually get it working. And I don't really want to. Rather, let's all file bug reports to get Apple to create an API that allows us to get more precise input from the keyboard.

Answer 2

In iOS 7, the UIResponder property keyCommands and the class UIKeyCommand were added to support shortcuts. Simply override keyCommands to return an array of UIKeyCommand and you should be good to go.