In general, the most common characters and symbols in the English language are easily accessible on the default iPhone keyboard — just tap on any text field to pull it up, tap the "123" button ...
Have you ever looked at the back of your iPhone and thought, "What do all these random symbols and numbers even mean?" Well — here's what each one means, and why they're even there in the first ...
Of course, there are a ton of other shortcuts on the iPhone that you may be missing out on. Rather than a system-wide button or symbol for undo on iOS, you just shake your phone or iPad.