Is the 1st argument of an Objective C variadic function mandatory?

Question

Here is an example of a variadic function in Obj C.

// This method takes an object and a variable number of args
- (voi         


        

Answer 1

The Objective-C way to implement variadic args is the same as in standard C. So you can pass in non-Objective-C object arguments.
Personally I'd use the first non-hidden arg to pass in the length of the following variadic list (for non-Objective-C objects - otherwise I'd use nil-termination)

- (void)appendIntegers:(NSInteger)count, ...
{
    va_list arguments;
    //the start of our variadic arguments is after the mandatory first argument    
    va_start(arguments, count);
    for(NSUInteger i = 0; i < count; ++i)
    {
        //to add the non-object type variadic arg, wrap it in a NSNumber object
        [list addObject:[NSNumber numberWithInteger:va_arg(arguments, NSInteger)]];
    }
    va_end(arguments);
    NSLog(@"%@", list);
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    list = [NSMutableArray array];
    [self appendIntegers:3 /* count */, 1, 2, 3];
}