By default, the caps lock feature on the iPhone keyboard is disabled. If you do a lot of shouting in your emails, you’ll want to be able to lock the shift button down. Here’s how.
The more I use the iPhone keyboard, the more I like it. There are not a lot of configurable options as of release date, but I imagine that will change as Apple receives feedback.
To enable CAPS LOCK on the iPhone, tap the Settings icon on the home screen, then tap the General button on the next screen.
In the general settings screen, tap on the Keyboard button.
In the keyboard settings screen, tap on or slide the switch to the right of Enable Caps Lock.
Caps Lock Use:
Enabling the caps lock feature doesn’t change the appearance of the keyboard. Instead, the caps lock feature is accessed with the standard shift key. If you quickly tap the shift key twice it will turn blue indicating that it is now in caps lock mode. You may need to try this a few times before you get it right.
Once you are done with your email rant, simply tap the shift key again to get out of caps lock mode.