Swift - Two variables in one if statement

I'm only a few days into learning swift and I've done a bit of research but either don't understand the explanations or I can't find what I'm looking for.

If I have two variable in an if statement, how can I tell if either variable is a nil value.

For example: (syntax is not correct but just giving an idea).

if variable1 or variable2 != nil { 
    // Do this 
} else {
    // Do this instead 
}

I need to know how to do the 'or' part of it.

I saw somewhere I could use || (2 x pipes) but it didn't work for me.

I would also like to know if the same would work for something other than variables such as.

if inputTextBox1.text or inputTextBox2.text != nil { 
    // Do this
} else { 
    // Do this instead
}

Thanks,

Toby