WriteUp - with Dropbox ($1.99) by Prasanna Gopalakrishnan is a text editor for your iPhone and iPad.
The App Store has a plethora of writing apps, so choosing the right tool for yourself can be difficult. But if you're looking for something simple that syncs with Dropbox with support for multiple folders, Markdown, and is a universal app, then WriteUp could be what you've been looking for.
The first thing you'll notice with WriteUp is that there's a help document for you when it's launched. Read this for a quick tour, and then you're off to writing!
The first thing you'll want to do is to setup your Dropbox account. This is accessible via the Settings button, represented by the familiar gear icon. Once you get your account set up, you can create nested folders to organize your text files with the New Folder button. When you're ready to create a new text document, just select the button.
When typing your text, you can select what type of font and size works best for you. The background is light and slightly textured. WriteUp automatically syncs changes with Dropbox every few minutes, and even when you hide the keyboard or go back to the folder view. Since there's not really a manual sync button, you can be ensured that all your work will be saved without worrying and checking every minute or so. No more "oh dang did I save it?!" moments.
There is a full screen mode as well that will get rid of the bar at the top as well as the bottom toolbar. Those familiar with John Gruber's Markdown syntax will be happy to know that WriteUp supports Markdown in the editing mode. To access the Markdown preview, you'll just have to be in the regular view mode and tap the (md) button. This button will change to (text) for you to go back to the regular editing mode. A document can also be emailed, in which the text will be copied into the body of the message.
I mentioned that you can change the font and size in the Settings. You can also adjust the sorting order and even have a Windows-friendly CRLF setting if desired.
Once you have a lot of text documents, it can be hard to go back and look for something, right? Luckily, WriteUp has a real-time search function that allows you to search through all of your documents, full body-text included. Searching through all of your notes is super easy!
WriteUp is pretty well done for what it's worth. Though if anything could be changed I would like to see different options for background and text color. While the off-white textured background is nice, some people would prefer something like light text on dark background and the like. More choices would be nice to see.
Other Dropbox text editors allow users to view character and word count - I hope something like that in the future.
I did encounter several crashes during my testing of the app, once after coming back to the document after it was on auto-lock for a while and another during Markdown preview while switching to landscape mode. Hopefully the crashes and bugs can be fixed in a future update.
Despite that, I have no other problems with WriteUp. If you're still in search of a Dropbox text editor with Markdown support and full-screen view, then check out WriteUp. It also works on both your iPad and iPhone.