objective-c 如何更新 NSMutableDictionary？

How to update NSMutableDictionary?

提问by S.P.

I have an NSMutableDictionary.

我有一个 NSMutableDictionary。

NSMutableDictionary* plistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:path];

I have to update an element in that dictionary. How i can do that?

我必须更新该字典中的一个元素。我怎么能这样做？

回答by Mihir Mathuria

Please refer to the APIhere

请参考此处的API

First retrieve the objects using

首先使用检索对象

[dict objectForKey:@"key"];

Later, you can set them back using:

稍后，您可以使用以下方法将它们重新设置：

- (void)setObject:(id)anObject forKey:(id)aKey
- (void)setValue:(id)value forKey:(NSString *)key

回答by pedrotorres

dictionary only allows you to have one objects for each key so if you use "set object for key" it will update the current one

字典只允许您为每个键拥有一个对象，因此如果您使用“为键设置对象”，它将更新当前的对象

回答by Renetik

NSMutableDictionary's method addEntriesFromDictionary.

NSMutableDictionary 的方法addEntriesFromDictionary。

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html

If both dictionaries contain the same key, the receiving dictionary's previous value object for that key is sent a release message, and the new value object takes its place.

如果两个字典都包含相同的键，则接收字典的该键的先前值对象将被发送一个释放消息，并且新值对象取代它。