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OC开发之——NSDictionary(58)

一 概述

  • NSDictionary又叫字典,类似于Java中的Map集合,一个key,有且只有一个对应的value
  • NSDictionary是不可变的,一旦初始化完毕后,里面的内容就无法修改
  • NSMutableDictionary是可变的,可向集合中添加新数据

二 NSDictionary的操作

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NSDictionary *dict=[NSDictionary dictionaryWithObject:@"jack" forKey:@"name"];
id obj=[dict objectForKey:@"name"];
NSLog(@"%@",obj);

NSArray *keys=@[@"name",@"address"];
NSArray *objects=@[@"jack",@"北京"];
NSDictionary *dicts=[NSDictionary dictionaryWithObjects:keys forKeys:objects];
NSDictionary *dicts2=[NSDictionary dictionaryWithObjectsAndKeys:
@"jack",@"name",
@"北京",@"address",
@"11111",@"qq",nil];
id obj2=[dicts2 objectForKey:@"qq"];
NSLog(@"%@",obj2);

NSDictionary *dict3=@{@"name": @"jack",@"address": @"北京"};
id obj3=[dict3 objectForKey:@"name"];
NSLog(@"%@",obj3);

id obj4=dict3[@"name"];
NSLog(@"%@",obj4);
NSLog(@"%d",dict3.count);

三 NSMutableDictionary的操作

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NSMutableDictionary *mdict=[NSMutableDictionary dictionary];
[mdict setObject:@"jack" forKey:@"name"];
[mdict setObject:@"北京" forKey:@"addredd"];
[mdict setObject:@"rose" forKey:@"name"];

NSString *str= mdict[@"name"];
NSLog(@"%@",str);
[mdict removeObjectForKey:@"name"];
NSLog(@"%@",mdict);

四 Dictionary的遍历

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NSDictionary *dict4=@{@"address":@"北京",
@"name":@"jack",
@"qq":@"121212",
@"address":@"北京",
@"name":@"jack",
@"qq":@"121212"};
NSArray *keys2=[dict4 allKeys];
for (int i=0; i<dict4.count; i++)
{
NSString *key= keys2[i];
NSString *object= dict4[key];
NSLog(@"%@=%@",key,object);
}

[dict4 enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, id _Nonnull obj, BOOL * _Nonnull stop)
{
NSLog(@"%@=%@",key,obj);
}];