I am trying to check if a textbox has no value.
When I do this:
if(userEmail?.isEmpty || userPassword?.isEmpty || userPasswordRepeat?.isEmpty)
I tried adding "?" before the ".isEmpty" but the error won't go away

Any ideas?
Try this....
if txtEmail.text?.isEmpty == true || txtPassword.text?.isEmpty == true || txtRePassword.text?.isEmpty == true{
print("true")
}
!to unwrap a value and read up on optional valuestextfield.textandtextfield.stringValue?stringValuestringValueproperty is not a member of textfiled when your develop app for iPhone or iPad...is available in mac app