Swizzle

gistfile1.m

// Don't forget to #import <objc/runtime.h>
void A2Swizzle(Class cls, SEL oldSel, SEL newSel, BOOL isClassMethod)
{
	if (isClassMethod) cls = object_getClass(cls);
	
	Method origMethod = class_getInstanceMethod(cls, oldSel);
	Method newMethod = class_getInstanceMethod(cls, newSel);
	
	if (class_addMethod(cls, oldSel, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
		class_replaceMethod(cls, newSel, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
	else
		method_exchangeImplementations(origMethod, newMethod);
}