Objective-C: Why should one check for != nil

Question

I often see code like this:

// Approach 1
if(data != nil){
    // Do this and that
}

When one could simply do the check like this:

Answer 1

This is mostly a style preference, or some people does not know that it is possible to use first solution.

Moreover, they are languages like java where you can't write the second solution, You must write yourVar != null