The same phonetic guide feature available in Pages (see yesterday’s post) works in Keynote for iOS! Also, I forgot to mention in the Pages post that you can add phonetic guide text (aka ruby text) in zhuyin (bopomofo) as well as pinyin! So you can use either pinyin or zhuyin in both Pages and Keynote. You can see zhuyin in the screenshot from Keynote on an iPhone, below.
A couple of notes on formatting: the guide text will take on the color of the main text. It seems as if you must set your main font text size before adding the phonetic guide; after the guide text is added, the text wouldn’t resize properly in my testing. Also in my quick test, centering seemed thrown off by the guide text and had to be adjusted by eye.
It’s still disappointing that you lose the phonetic guide text if you open the file in Keynote for Mac (as with Pages). It would be nice if there were at least a fallback, like the treatment of ruby text in web browsers. I did discover, however, that if you choose to download a pdf of your Keynote from iCloud (rather than a Keynote file), the guide text will appear in the pdf.
Drawbacks aside, given the popularity of the iPad especially as a teaching and learning tool, this is an extremely welcome and useful feature for Asian language pedagogy.