替换 NSDictionary 中的键/值
如果我有一个带有以下键/值“foo”/“bar”的字典并声明 [dictionary setObject:@"baz" forKey:@"foo"]; 这会替换当前的键值与“foo”/“baz”配对并删除“foo”/“bar”？
If I have a dictionary with the following key/value "foo"/"bar" and declared [dictionary setObject:@"baz" forKey:@"foo"]; would this replace the current key value pair with "foo"/"baz" and delete "foo"/"bar"?
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NSMutableDictionary（与任何常见的哈希表一样）的行为是，如果它不存在，它会创建一个新的键/值对，如果它已经存在，它将用新值替换现有值。
The behave of an NSMutableDictionary (as any common hash table) is that if it does not exists it creates a new key/value pair, if it already exits it will replace the existing value with the new one.
文档在这里；
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html%23//apple_ref/doc/uid/TP40003692
表明会的。但请不要相信我的话，你自己读一下。
也许你还应该阅读；
http ://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Collections/Collections.html%23//apple_ref/doc/uid/10000034i
The documentation here;
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html%23//apple_ref/doc/uid/TP40003692
suggests that it would. But please, don't take my word for it, read them yourself.
Perhaps you should also read;
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Collections/Collections.html%23//apple_ref/doc/uid/10000034i