ObjC Hachik

Hachik.h

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

template <typename RET, typename ...Types>
class ObjcMethodHook {
    typedef RET(*_IMP)(id _self, SEL _cmd, Types...);
    typedef RET(^_IMPBlock)(id _self, Types...);

private:
    Class m_cls;
    SEL m_sel;
    _IMP m_orig;

public:
    ObjcMethodHook(Class cls, SEL sel) : m_cls(cls), m_sel(sel), m_orig(NULL) {};
    ObjcMethodHook(const char *cls, const char *sel) : ObjcMethodHook(objc_lookUpClass(cls), sel_getUid(sel)) {};

    void hook(_IMPBlock imp) {
        Method m = class_getInstanceMethod(m_cls, m_sel);
        m = class_getInstanceMethod(m_cls, m_sel);

        m_orig = (_IMP)class_replaceMethod(m_cls, m_sel, imp_implementationWithBlock(imp), method_getTypeEncoding(m));
    };

    RET super(id _self, Types... args) {
        if (m_orig) {
            return m_orig(_self, m_sel, args...);
        } else {
            struct objc_super s = {
                _self,
                class_getSuperclass(m_cls)
            };
            return ((_IMP)objc_msgSendSuper)((__bridge id)&s, m_sel, args...);
        }
    };

    RET call(id _self, Types... args) {
        return ((_IMP)objc_msgSend)(_self, m_sel, args...);
    }
};