Objective-C indentation in emacs

Question

I'm using Emacs to edit my Objective-C code. The default indentation looks like this:

    NSTimer *timer =
        [NSTimer timerWithTimeInterval:1.0
                 target:self
                 selector:@selector(callback:)
                 userInfo:nil 
                 repeats:YES];

I would like Emacs to indent the code like XCode, that is, to align with the colons:

    NSTimer *timer =
        [NSTimer timerWithTimeInterval:1.0
                                target:self
                              selector:@selector(callback:)
                              userInfo:nil 
                               repeats:YES];

Is there any hope to achieve this?

Answer 1

I've been hacking on this for a bit and have gotten closer, but it's not fully functional yet. The solution I have is to add an entry to align-rules-list , so that a simple Mx align will do the trick. The problem is that you have to run align twice in order to get it to work.

(obj-c-colons
 (regexp . "^\\(\\s-*[^:]+\\):")
 (justify . t)
 (repeat . t)
 (modes obj-c-mode)) ;; <= Replace with actual name of major mode

I don't actually know what the name of the objective-c mode is, so you will have to replace obj-c-mode with whatever the mode is actually called. You can add this to align-rules-list with:

(add-to-list 'align-rules-list
             '(obj-c-colons
               (regexp . "^\\(\\s-*[^:]+\\):")
               (justify . t)
               (repeat . t)
               (modes obj-c-mode)))

For now, you have to execute align twice; the first time will only line it up as follows:

 NSTimer *timer =
        [NSTimer timerWithTimeInterval:1.0
                              target:self
                            selector:@selector(callback:)
                            userInfo:nil
                             repeats:YES];

Notice that the colons are two characters too far to the left. The second align will correct this. Don't ask me why.

There is a lot that goes on with the align command, so figuring it out is hard. Hopefully someone comes up with a way to improve upon this. Anyway, take a look at the relevant EmacsWiki page for more info on aligning.

Answer 2

在c-offsets-alist中，ob -c-method-call-colons的c-lineup-ObjC-method-call-colons是否有问题？

Answer 3

There is a Objective C mode that does this here

Here is what it looks like