Make NSInvocation from object, selector and array of arguments.

OperationWithInvocation.m

// invocaion and operation 

#import <Foundation/Foundation.h>	
NSInvocation* XSMakeInvocation(id obj, SEL aSelector, NSArray *args);



int main(int argc, char const *argv[])
{
	@autoreleasepool{
		NSMutableString *s = [NSMutableString string];
		NSInvocation *v = XSMakeInvocation(s, @selector(appendString:), @[@"This is good."]);
		[v invoke];
		NSLog(@"%@",s);
	}
	return 0;
}



NSInvocation* XSMakeInvocation(id obj, SEL aSelector, NSArray *args) 
{
	NSInvocation *anInvocation;
	NSMethodSignature *sig;
	NSUInteger i;
	sig = [obj methodSignatureForSelector:aSelector];
	anInvocation = [NSInvocation invocationWithMethodSignature:sig];
	[anInvocation setSelector:aSelector];
	[anInvocation setTarget:obj];
	for(i=0;i<[sig numberOfArguments]-2;i++) {
		id argv = [args objectAtIndex:i];
		[anInvocation setArgument:&argv atIndex:i+2];
	}
	return anInvocation;
}