如何获取 Objective-C 字典中每个键的值？

我正在维护一个NSMutableDictionary它保存键和值对。现在我需要对其中的每个值执行一些操作。如何从字典中检索值。

// this is NSMutableDIctionary 
NSMutableDictionary *dictobj = [[NSMutableDictionary alloc]init];
 // in methodA

-(void)methodA
{
   //get the value for each key and peform an operation on it.
}

如何进行？请帮忙

for (id key in dictobj)
{
    id value = [dictobj objectForKey:key];
    [value doSomething];
}