// Code in this article:
// https://it.toolbox.com/blogs/hohlecow/bypassing-objective-cs-message-passing-mechanism-for-speed-052708

#import <Cocoa/Cocoa.h> 
@interface Fib : NSObject { 
} 
- (long long) messageFib: (NSUInteger) number;
- (long long) impFib: (NSUInteger) number; 
- (long long) cFib: (NSUInteger) number; 
@end 

@implementation Fib 

// message passing implementation of fib 
- (long long) messageFib: (NSUInteger) number { 
	return (number < 3) ? 1 : [self messageFib: number - 1] + [self messageFib: number - 2]; 
} 

// imp implementation of fib 
- (long long) impFib: (NSUInteger) number { 
	static long long (*impFibIMP)(id, SEL, NSUInteger) = nil; 
	if (!impFibIMP) { 
		impFibIMP = (long long (*)(id, SEL, NSUInteger)) [self methodForSelector: _cmd]; 
	} 
	return (number < 3) ? 1 : impFibIMP(self, _cmd, number - 1) + impFibIMP(self, _cmd, number - 2); 
} 

// c implementation of fib 
long long cFib(NSUInteger number) { 
	return (number < 3) ? 1 : cFib(number - 1) + cFib(number - 2); 
} 

// method wrapper for c implementation of fib 
- (long long) cFib: (NSUInteger) number { 
	return cFib(number); 
} 

@end