Is if(items != null) superfluous before foreach(T item in items)?

Question

I often come across code like the following:

if ( items != null)
{
   foreach(T item in items)
   {
        //...
   }
}

Basically, the

Answer 1

In C# 6 you can write sth like this:

// some string from file or UI, i.e.:
// a) string s = "Hello, World!";
// b) string s = "";
// ...
var items = s?.Split(new char[] { ',', '!', ' ' }) ?? Enumerable.Empty();  
foreach (var item in items)
{
    //..
}

It's basically Vlad Bezden's solution but using the ?? expression to always generate an array that is not null and therefore survives the foreach rather than having this check inside the foreach bracket.