We probably don't think too much about the apostrophe we use when typing and it probably doesn't bother us but I recently had an issue. On a forum, I've set up a user name (using my Mac) that includes one. All was well till I tried to log in using my phone. I couldn't! After double checking my name and password I came to the conclusion that it must be the apostrophe. The phone can offer you several versions if you hold your finger on the key but none of those worked either. I then discovered in Settings>General>Keyboards that Smart Punctuation was turned on. Turning it off gave me the same apostrophe as the Mac which allowed me to log in - it didn't look any different to the others I'd tried but clearly has its own character code.
Strowth! As it happens the keys on the Apple extendd keyboard have a different code to their counterparts on the 'standard' keyboard. My favourite shortcut in QuarkXpress had me foxed for quite a while. Thanks and sympathy :)
I believe the four characters in the iOS popup are, from left to right:
U+0060 GRAVE ACCENT, the character produced by the key to the left of Z on a UK hardware keyboard, or at the top-left of a US keyboard
U+2018 LEFT SINGLE QUOTATION MARK, the character produced by Option-] on a Mac
U+2019 RIGHT SINGLE QUOTATION MARK, the character produced by Shift-Option-] on a Mac
U+0027 APOSTROPHE, the character produced by the key beneath [ on a hardware keyboard
Presumably the last one, U+0027, was what you needed, but explicitly selecting that from the iOS popup seems to insert the expected character for me even when ‘smart’ punctuation is enabled. Perhaps it depends on the application?
It is annoying that U+2018 and U+2019 (the typographic quote characters inserted by ‘smart’ punctuation) are almost indistinguishable from each other in the San Francisco font, especially on a non-retina display.
To add to Andrew's comment: the keyboard key, for both ' and ", produces the old ASCII "sexless" quote characters. However, many programs (including Pages, for example) detect that, examine the context and substitute either a left or right quote/double quote to provide their "smart quotes" feature.
This is great typography and makes documents look much better but is a pain for character-matching tasks (like passwords).
Mick Burrell 