Object-c------NSDictionary的简单介绍

//
//  main.m
//  NSDictionary
//
//  Created by zhaogang on 16/5/8.
//  Copyright © 2016年 zhaogang. All rights reserved.
//
/*
集合
NSArray        ArrayList
NSSet          HashSet
NSDictionary   Map

1. NSArray\NSMutableArray
* 有序
* 快速创建(不可变): @[]
* 快速访问元素: 数组名[]

2. NSSet\NSMutableSet
*无序

3. NSDictionary\NSMutableDictionary
* 无序
* 快速创建(不可变): @{key : value}
* 快速访问: 字典名[key]

*/

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {

NSArray *person = @[
@{@"address" : @"beijing" , @"name" : @"jack", @"age" : @"22"},
@{@"address" : @"shanghai" , @"name" : @"rose", @"age" : @"21"},
@{@"address" : @"nanjing" , @"name" : @"mike", @"age" : @"23"},
@{@"address" : @"hongkong" , @"name" : @"hobe", @"age" : @"25"}

];

//    NSDictionary *jack = person[0];
//    NSLog(@"%@", jack);

NSLog(@"%@", person[1][@"address"]);

return 0;
}

void test3()
{
//字典不允许有想用的key，但允许有相同的value(object)
NSDictionary *dict = @{@"address" : @"beijing" , @"name" : @"jack", @"age" : @"22"};

//    NSArray *keys = [dict allKeys];
//    for(int i = 0; i < dict.count; i++)
//    {
//        //[keys objectAtIndex:i];
//        NSString *key =  keys[i];
//        NSString *object = dict[key];
//
//        NSLog(@"%@ - %@", key , object);
//    }

[dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
NSLog(@"%@ - %@" , key , obj);

//*stop = YES;
}];

}

void test2()
{

//错误
//    NSMutableDictionary *dict = @{@"name" : @"jack"};
//
//    [dict setObject:@"rose" forKey:@"name"];
NSMutableDictionary *dict = [NSMutableDictionary dictionary];

//添加键值对，没有顺序
[dict setObject:@"jack" forKey:@"name"];
[dict setObject:@"beijing" forKey:@"address"];

//这里会将上面的key的值覆盖
[dict setObject:@"rose" forKey:@"name"];

//移除键值对
//[dict removeObjectForKey:<#(nonnull id)#>];

NSString *str = dict[@"name"];

NSLog(@"%@",str);

//NSLog(@"%@", @[@"jack", @"rose"]);

NSLog(@"%@", dict);
}

void test()
{
/*
字典：

key－－－－>value
索引－－－－>文字内容

里面存储的东西都是键值对
*/

//NSDictionary *dict = [NSDictionary dictionaryWithObject:@"jack" forKey:@"name"];

//    NSArray *key = @[@"name", @"address"];
//    NSArray *object = @[@"jack", @"beijing"];
//
//    NSDictionary *dict = [NSDictionary dictionaryWithObjects:object forKeys:key];

//    NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
//                          @"jack",@"name",
//                          @"beijing",@"address",
//                          @"22",@"age",nil];

NSDictionary *dict  = @{@"name" : @"jack" , @"address" : @"beijing" , @"age" : @"22"};

id obj = [dict objectForKey:@"age"];
NSLog(@"%@", obj);

//返回键值队的个数
NSLog(@"%ld" , dict.count);

}