NSArray creation with variable argument lists

问题

This array convenience method takes a comma-separated list of objects ending with nil.

myArray = [NSArray arrayWithObjects:aDate, aValue, aString, nil];

What is the purpose of the nil?

回答1:

Null terminated variable argument lists, or va_lists, keep walking the list of arguments until they encounter a placeholder or sentinel, which is nil.

Since the method has no way of knowing how many arguments you are passing, it needs the sentinel (nil) to tell where the list ends.

回答2:

To mark the end of the list of objects.

Here's a discussion from CocoaBuilder.

来源：https://stackoverflow.com/questions/3602458/nsarray-creation-with-variable-argument-lists