NSObject+swizzle.m

NSObject+swizzle.m

#import <Foundation/Foundation.h>

@interface NSObject (Swizzle)



/**
 @brief Method that swizzles both instance methods and class methods
 @param fromMethod original selector
 @param toMethod method of destination in swizzling.
**/
+ (void) swizzleFromSelector:(SEL) fromMethod toSelector:(SEL) toMethod;

@end

@implementation NSObject (Swizzle)

+ (void) swizzleFromSelector:(SEL) fromMethod toSelector:(SEL) toMethod
{
    //check if methods are instance methods first
    Method origMethod = class_getInstanceMethod(self, fromMethod);
    Method newMethod = class_getInstanceMethod(self, toMethod);
    
    BOOL isClassMethod = NO;
    if (!origMethod)
    {
        origMethod = class_getClassMethod(self, fromMethod);
        isClassMethod = YES;
    }
    if (!newMethod)
    {
        newMethod = class_getClassMethod(self,toMethod);
        isClassMethod = YES;
    }
    
    
    //to only be used when method is a class method
    Class c = self;
    if (isClassMethod) {
        c = object_getClass((id) self);
    }
    

    
    if(class_addMethod(c, fromMethod, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
    {
        class_replaceMethod(c, toMethod, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    }
    else
    {
        method_exchangeImplementations(origMethod, newMethod);
    }
    
}

@end