objective-c - [NSMutableDictionary dictionaryWithDictionary :] and mutableCopy? 之间有区别吗

Question

以下创建可变字典的方式有区别吗？

NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithDictionary:dict2];

NSMutableDictionary *dict = [dict2 mutableCopy]

Answer 1

如果dict2为nil，[NSMutableDictionary dictionaryWithDictionary:dict2]将返回一个空字典和[dict2 mutableCopy] 将返回 nil。