performSelector与objc_msgSend

- perform:(SEL)aSelector

{

if (aSelector)

return objc_msgSend(self, aSelector);

else

return [self error:_errBadSel, sel_getName(_cmd), aSelector];

}

- perform:(SEL)aSelector with:anObject

{

if (aSelector)

return objc_msgSend(self, aSelector, anObject);

else

return [self error:_errBadSel, sel_getName(_cmd), aSelector];

}

- perform:(SEL)aSelector with:obj1 with:obj2

{

if (aSelector)

return objc_msgSend(self, aSelector, obj1, obj2);

else

return [self error:_errBadSel, sel_getName(_cmd), aSelector];

}

https://opensource.apple.com/source/objc4/objc4-493.9/runtime/