Objective-C selector swizzle

Swizzle

// ************************************************************ //
// NSObject + Swizzle.h
// ************************************************************ //

@interface NSObject (Swizzle)

+ (void)swizzleSelector:(SEL)selector withSelector:(SEL)newSelector;

@end


// ************************************************************ //
// NSObject + Swizzle.m
// ************************************************************ //

#import "NSObject+Swizzle.h"

#import <objc/runtime.h>

@implementation NSObject (Swizzle)

+ (void)swizzleSelector:(SEL)selector withSelector:(SEL)newSelector
{
    Method originalMethod = class_getInstanceMethod(self, selector);
    Method newMethod = class_getInstanceMethod(self, newSelector);
    
    BOOL methodAdded = class_addMethod([self class],
                                       selector,
                                       method_getImplementation(newMethod),
                                       method_getTypeEncoding(newMethod));
    
    if (methodAdded)
    {
        class_replaceMethod([self class],
                            newSelector,
                            method_getImplementation(originalMethod),
                            method_getTypeEncoding(originalMethod));
    }
    else
    {
        method_exchangeImplementations(originalMethod, newMethod);
    }
}

@end