How can I quickly type special characters on an iPhone/iPad using a bluetooth keyboard?
You can use the same keyboard combinations as on OS X to create accented characters. Here are the commands for each:


⌥+` then a=à
⌥+e then a=á
⌥+u then a=ä
⌥+i then a=â
⌥+n then a=ã


After you press the ⌥ (option/alt key) combination, the accent character will show up. Then, typing the next character will replace the accent with the accented character, if possible. If the character you type cannot have that accent, the accent will stay, followed by the character.