Dictionary of Objective-c explaining

We have learned from childhood, the dictionary has always been a good helper of our study, in OC the dictionary still has its irreplaceable role, and now we will go through her mysterious veil ...

Advantages of the Dictionary:

1. A dictionary is a collection of keywords and their corresponding values

2.NSDictionary stores a data under a given keyword, which can be any of the OC object types

3. The data in the dictionary always appears in pairs, all keys and values are pre-set and can only be found within this range

4. The corresponding data can be accessed by the keyword

Disadvantages of the Dictionary:

1. The output of the dictionary is unordered, so he cannot be sorted

2. A key can only correspond to a value, the contents of the search can only be pre-set;

Now the dictionary is explained in detail:

Now output the result of the operation:

Dictionary of Objective-c explaining