I have an iOS app with two `UITextFields` which allow the user to manually enter latitude and longitude co-ordinates. One thing I am puzzled about is, how can I make sure the entered data is a valid coordinate?

* Coordinates much be numbers only
* Coordinates can have a minus sign.
* Coordinates cannot have spaces in them.

Would you say there are any other checks I should do? 

And how can I check if the `UITextField.text` have letters as well as numbers? Could I use Regex?

**Update**

So to clarify my question these are the types of strings I am trying to check:

* -2.42353463466 (Valid)
* 32.131ertf22 (Not valid - it contains characters)
* 1.23141 4124 (Not valid - it contains spaces)