I started to use the editor inside Xcode for entering Objective-C code, but then I saw an editor called TextMate that seems to be very good for entering code. It has many shortcuts and seems to be well thought out. Like any new application, it takes effort to learn and get used to, so I’m uncertain if it’s worth investing in. And also I’m uncertain if it integrates into Xcode, but I suspect it does. People who made Xcode would be dumb not to let people choose their editor of choice. Any suggestions?
My suspicion was right, you can choose any external editor. Just open Xcode and follow the following path:
Xcode/Preferences…/File Types/file/text/sourcecode
and then choose TextMate (or any other) as your External Editor.
What seems funky with TextMate is that you can program it to work as you prefer. The simplest way to do it is using snippets, which takes 10 minutes to learn. However I’m still experimenting with TextMate and I’m not yet ready to recommend it or choose it instead of the built in Editor in Xcode. If you have any experience in this area please let me know.
Maybe this post belongs to, “Software by Other Folk”, but I’ve put it here because my current interest is learning Cocoa and choosing the best editor for entering Objective-C code.
I have been using TextMate for a couple of months now and I think it’s terrific 8). Better then the editor provided in Xcode. You just drag your project icon to the drawer of TextMate and boom you’ve got all the files in TextMate which you can manipulate just as in your dreams. And when you save in TextMate it is automatically saved in Xcode. To get maximal benefit and avoid clutter I use condensed Layout (see Xcode/Preferences…). Also I use Spaces so Xcode and TextMate go in one space while IB goes in another space.
Every person have different opinion about code editing sotwares. First I was using DW Micromedia 8. But from last couple of months I am using Adobe Dream Veiwer 5. Really these software are costly and unable to change ASAP as they release. 
TextMate is pretty much a classic these days. Development is slow, but frankly there is little about it that I feel needs to be changed (mainly, the single-character undo). I’ve been using it for about a decade or so, and at this point in time have a huge catalogue of scripts and macros I’ve programmed into it. The only thing that can draw me away from it is Vim.
Guilty admission time… Eclipse. I’ve gone over to the dark side. The thing for me is all the various platforms and languages I’m using are supported (C/C++, ASM, PHP, Perl, Java) as well as easy cross compiling for different architectures (AVR, PIC, Intel, Sparc, ARM). Yes it is a monster to figure out and it is a bit restrictive once you get into it, but it gives me all the things I really want in an editor but with the IDE bells and whistles.