Merge pull request #1796 from NativeScript/nsrange-exception

Fix NSRangeException when typing in a TextField with formatted text

ui/text-field/text-field.ios.ts

@@ -82,11 +82,13 @@ class UITextFieldDelegateImpl extends NSObject implements UITextFieldDelegate {
                     owner._onPropertyChangedFromNative(TextBase.textProperty, replacementString);
                 }
                 else {
+                    if (range.location <= textField.text.length) {
                         let newText = NSString.alloc().initWithString(textField.text).stringByReplacingCharactersInRangeWithString(range, replacementString);
                         owner._onPropertyChangedFromNative(TextBase.textProperty, newText);
                     }
                 }
             }
+        }
 
         this.firstEdit = false;
         return true;