runtime.py 文件源码

def add_method(cls_name, selector_name, fn, type_encoding):
    cls = ObjCClass(cls_name).ptr

    selector = sel(selector_name)

    if c.class_getInstanceMethod(cls, selector):
        error('Failed to add method, class {} already provides method {}'.format(cls_name, selector_name))
        return

    parsed_types = parse_types(type_encoding)
    restype = parsed_types[0]
    argtypes = parsed_types[1]

    IMPTYPE = CFUNCTYPE(restype, *argtypes)
    imp = IMPTYPE(fn)
    retain_global(imp)

    did_add = c.class_addMethod(cls, selector, imp, c_char_p(type_encoding.encode('utf-8')))
    if not did_add:
        error('Failed to add class method')

    return did_add