You can configure them either programmatically or using the attribute inspector of Interface Builder. If there is only one text object in the currently displayed view, the identity of the text object referenced by the parameter is obvious.
Sanitization is a bit more liberal of an approach to accepting user data.
We can fall back to using these methods when there's a range of acceptable input.
The intval() function casts user input as an integer, and defaults to zero if the input was a non-numeric value.
We then check to see if the value ended up as zero.
Word Press thankfully has a few helper functions we can use for most of what we'll commonly need to do: esc_html() we should use anytime our HTML element encloses a section of data we're outputting.