gistfile1.m

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

@interface Test: NSObject
@end

@interface Test (Dynamic)

- (void)foo:(float)x :(float)y;

@end


@implementation Test

+ (BOOL)resolveInstanceMethod:(SEL)sel
{
    if (sel == @selector(foo::))
    {
        IMP imp = imp_implementationWithBlock(^(Test *self, float x, float y){
            NSLog(@"%g, %g", x, y);
        });
        class_addMethod(self, sel, imp, (const char []){ _C_ID, _C_SEL, _C_FLT, _C_FLT });
        return YES;
    }
    else
    {
        return [super resolveInstanceMethod:sel];
    }
}

@end



int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        Test *t = [[Test alloc] init];
        [t foo:5 :42.3];
    }
    return 0;
}