both are different iOS and Mac OS. so you use the iphone keyboard directly, don't use the system keyboard, and both can be different functions for different keyboard shortcuts

set the keyboard type of the text field
[textField setKeyboardType:UIKeyboardTypeEmailAddress]
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On Macintosh OS X, you can use the operating system character palette to find special characters. Press the + option + T command to display the character palette window.
The character palette will also be displayed as a menu item in the keyboard menu if the keyboard menu is displayed in the upper right corner of the menu bar. The keyboard menu is displayed as a flag corresponding to the currently active keyboard layout.
New answer
Writer for iPad and iPhone includes a keyboard expansion panel that gives you navigation buttons as well as quick access to language punctuation. The keyboard has localized keys for the following keyboards in Writer for iPad: Arabic, Simplified Chinese, Traditional Chinese, Croatian, Dutch, English, French, Swiss French, Canadian French, German, Swiss German, Greek, Italian, Japanese, Latvian, Polish, Portuguese , Romanian, Russian, Spanish and Ukrainian.
Here are some other ways to enter special characters, both on iOS and Mac OS X.
http://support.iawriter.com/help/kb/general-questions/typing-spe