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I would like to build something similar to the code-completion feature in Xcode 4. (The visual style and behavior, not the data structure type work required for code completion).

As the user is typing, a pop-up window presents other word choices that can be selected.

The Feature in action:

Code-Completion window in action.

I'm not exactly sure where to start. I am mainly concerned with the visual appearance of the window and how I should populate the list with a given set of words. Later I will get into making the window follow the cursor around the screen and etc.

I am mainly looking for an overview of how to display such data in a "window", and how to cusomize the appearance of the thing so it looks like a nice little informational popup rather than a full-on OS X window.

ck_
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2 Answers2

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Just add a subview to your current view that happens to be a tableview. Programmatically cause it to be visible on an event (such as mouseDown), and adjust it's position based on where you want it. You will need to instantiate the proper delegate/datasource methods, but it should be pretty straight forward. You will also need a source for the words you want to use in your autocomplete, and put them in an array or something for your tableview datasource to go through.

Like I said, it's not terribly hard, provided you are comfortable using tableviews and adding views to your existing view. If this doesn't explain enough, leave a comment and I can flesh this comment out more.

JoeCortopassi
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  • Sorry, iOS brain took over. Instead of touchdown, whatever event you want to tie into. And yeah, should have been datasource instead of delegate. I'll edit for clarity – JoeCortopassi Feb 16 '12 at 19:03
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Add a (completions) subview to your view and set its visible property to NO. Create a separate AutoComplete object that includes the subview as a property and fills it with potential completions. Your controller can respond to key pressed (key typed) events and give the last word (substring the text from the end to the 1st preceding blank) to the AutoComplete on each event. The basic logic in AutoComplete could be something like:

Given an AutoComplete with a list of known words "dog, spaghetti, minute, horse, spare, speed" When asked to complete a fragment "sp" Then the following words should be offered as potential completions, "spaghetti, spare, speed"

Which would imply that you need to instantiate it with a list of words (this could be done in the init of your controller), and create a method "-(NSArray*) completeFragment:(NSString*)fragment;". You could drop this into an OCUnit test case and iterate over your implementation of autocomplete until you get it right. You would then write a method that takes the completions from AutoComplete and lists them in the subview. Even better you might create currentWord and potentialCompletions properties in AutoComplete that gets updated as you send it "newFragment:(NSString*)fragment;" messages. Throw that into OCUnit and work it out then use that potentialCompletions property to drive updated of a the subview (which is probably best modeled as a custom tableView).

Cliff
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