performSelector reimplementation with variable number of params/types and return type.

NSObject-extension.m

/*
   You can use this to call deprecated methods without warnings (supporting old sdk's for example)
   or, you can use it in place of performSelector: where you need non-object params, or multiple
   params.

   ie: ...

   int result = 0;
   int index = 12;
   NSArray *array = myArray;
   result = [self performSelector:@selector(checkSomething:atIndex:) returnAddress:&result argumentAddresses:&array, &index];

*/

- (void)performSelector:(SEL)aSelector returnAddress:(void *)result argumentAddresses:(void *)arg1, ...
{
	va_list args;
	va_start(args, arg1);
	
	if([self respondsToSelector:aSelector])
	{
		NSMethodSignature *methodSig = [[self class] instanceMethodSignatureForSelector:aSelector];
		NSInvocation *invocation = [NSInvocation invocationWithMethodSignature: methodSig];
		[invocation setTarget:self];
		[invocation setSelector:aSelector];
		if (arg1)
			[invocation setArgument:arg1 atIndex:2];
		void *theArg = nil;
		for (int i = 3; i < [methodSig numberOfArguments]; i++)
		{
			theArg = va_arg(args, void *);
			if (theArg)
				[invocation setArgument:theArg atIndex:i];
		}
		[invocation invoke];	
		if (result)
			[invocation getReturnValue:result];
	}
	
	va_end(args);
}

just fixed a misplaced &. get le new one.

Wouldn't setting result = ... give a warning since it's a void method? I realize that's the point of passing it by reference to returnAddress, but setting it when called seems like a typo. I may be way off. I'd love an explanation either way :)

sorry, missed this.

not sure i follow. if result is nil when passed in, it's not going to try and set it post invoke. if you give a return value and the selector's return is void, then yes, you may see problems.

though, now that i'm looking at the return a little more.. it is assuming result's size, which i should fix.