articles - "A" vs. "An" in writing vs. pronunciation

When starting a word with a vowel, the preceding "a" becomes an "an". I often find that when writing words that start with letter "N" or "M", I will pronounce them "EN", "EM", etc. (This is because in programming, letters are often pronounced in certain terms.)

So, when writing a question on SO, do I write "an NSString" or, "a NSString"?

Answer

The choice of a vs. an is actually based on the phonetics of the start of a word, not the orthographic representation. This is why you say things like an honorable solider (the h is silent, so phonetically it begins with the vowel sound). Similarly, you would say a one-eyed pirate as one phonetically begins with the w sound.

So in the case of your example, it would be an NSString since phonetically it's en-es-string.