NSDictionaryNSMutableDictionary
@interface NSMutableDictionary<KeyType, ObjectType> : NSDictionary<KeyType, ObjectType>
同数组---NSDictionary的特性，NSMutableDictionary同样继承
字典：
key -----> value
索引 ----> 文字内容
存储键值对
一、创建字典
NSDictionary *dict = [NSDictionary dictionaryWithObject:@"字典" forKey:@"name"];
即
NSArray *key...