NSMutableArray，alloc或capacity？ [英] NSMutableArray, alloc or capacity?

问题描述

除了返回自动释放对象和其他需要手动释放的对象之外，是否有任何理由去使用这两个对象？

Is there any reason to go with either of these, other than one returning an autoreleased object and the other needing a manual release?

NSMutableDictionary *drink = [[NSMutableDictionary alloc] init];
// do things ...
[drink release];

或

NSMutableDictionary *drink = [NSMutableDictionary dictionaryWithCapacity:10];

gary

推荐答案

这些是方便的方法，有助于减少你必须写的代码量，并在某些情况下有帮助。

These are convenience methods that are useful for reducing the amount of code you have to write, and are there to help in certain circumstances.

除了+ dictionaryWithCapacity：和+字典方法将被自动释放外，所获得的对象没有真正的区别，而-init返回的对象不会。

The object you get will have no real differences other than that the +dictionaryWithCapacity: and +dictionary methods will be autoreleased, and the one returned by -init won't.

另外，如果你知道有多少项将被放入字典，+ dictionaryWithCapacity：和-initWithCapacity：将提高效率，因为字典会能够在蝙蝠上分配正确的内存量。

As an aside, if you know how many items will be put into the dictionary, +dictionaryWithCapacity: and -initWithCapacity: will provide a slight boost in efficiency since the dictionary will be able to allocate the right amount of memory right off the bat.

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