Handly method swizzling method

MethodSwizzle.m

// Original Reference: http://stackoverflow.com/questions/1637604/method-swizzle-on-iphone-device

#import <objc/runtime.h> 
#import <objc/message.h>
//....

void Swizzle(Class c, SEL orig, SEL new)
{
    Method origMethod = class_getInstanceMethod(c, orig);
    Method newMethod = class_getInstanceMethod(c, new);
    if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    else
    method_exchangeImplementations(origMethod, newMethod);
}