Is it ok to cast a NSdictionary object to NSMutableDictionary?

Is it ok to cast a NSdictionary object to NSMutableDictionary?

NSDictionary *dict;
NSMutableDictionary *mDict = (NSMutabl开发者_开发百科eDictionary *)dict;

Tried this and it worked fine.

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No it is not. If you want a mutable dictionary, make one:

NSMutableDictionary* mutableDict = [dict mutableCopy];

Do not forget in accordance with the rules you own mutableDict and must release it when you are done with it.