day05-04-字典

Objective-c

//  main.m
//  day05-04-字典
//
//  Created by Aaron on 15/7/7.
//  Copyright (c) 2015年 Aaron. All rights reserved.
//
#import <Foundation/Foundation.h>
//字典
//键值对
//key----value
//键值对成对出现
//一一对应
//哈希
//key必须是唯一的
//value可以是多个
//里面存储的都只能是对象
//NSDictionary
//NSMutableDictionary
#if 0
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSDictionary *dic = [[NSDictionary alloc] init];
        //用键值对来初始化字典
        //注意:值在前,键在后,成对出现
        //没有顺序
        NSDictionary *dic1 = [[NSDictionary alloc] initWithObjectsAndKeys:@1,@"one",@2,@"two",@3,@"three", nil];
        NSLog(@"%@",dic1);
        NSArray *valueArray = @[@1,@2,@3,@4];
        NSArray *keyArray = @[@"one",@"three",@"four",@"two"];
        //用键值对数组来初始化字典
        NSDictionary *dic2 = [[NSDictionary alloc] initWithObjects:valueArray forKeys:keyArray];
        NSLog(@"%@",dic2);
        NSDictionary *dic3 = [[NSDictionary alloc] initWithDictionary:dic2];
        //NSDictionary *dic4 = [NSDictionary dic]
        //类方法创建字典
        //2.0新特性
        //@{key:value,key:value....}
    }
    return 0;
}
#endif
#if 0
int main()
{
    //常用的方法
    NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@1,@"one",@1,@"three",@2,@"two", nil];
    //获取键值对的个数
    NSInteger count = [dic count];
    NSLog(@"%ld",count);
    //获取key对应的value
    id obj = [dic objectForKey:@"one"];
    NSLog(@"%@",obj);
    //获取值对应的键
    NSArray *keys = [dic allKeysForObject:@1];
    NSLog(@"%@",keys);
    //获取所有的键
    NSArray *allKeys = [dic allKeys];
    NSLog(@"%@",allKeys);
    //获取所有的值
    NSArray *objs = [dic allValues];
    NSLog(@"%@",objs);
}
#endif
//字典的遍历
#if 0
int main()
{
    NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@1,@"one",@1,@"three",@2,@"two", nil];
    //for in快速遍历
    for(id obj in dic)
    {
        //遍历出来的是key
        NSLog(@"%@",obj);
    }
    NSEnumerator *enumerator = [dic keyEnumerator];
    enumerator = [dic objectEnumerator];
    id obj = nil;
    while(obj = [enumerator nextObject])
    {
        NSLog(@"%@",obj);
    }
}
#endif
int main()
{
    //可变字典
    NSMutableDictionary *dic = [NSMutableDictionary dictionary];
    //增删改
    //添加键值对其实是设置一对键值对
    [dic setObject:@10 forKey:@"ten"];
    NSLog(@"%@",dic);
    //从另外一个字典里将键值对添加到当前字典
    [dic addEntriesFromDictionary:@{@"two":@2}];
    NSLog(@"%@",dic);
    //修改
    [dic setObject:@22 forKey:@"two"];
    NSLog(@"%@",dic);
    //删除
    //删掉key所对应的键值对
//    [dic removeObjectForKey:@"two"];
//    [dic removeObjectsForKeys:@[@"ten",@"two"]];
    [dic removeAllObjects];
    [dic setDictionary:@{}];
    NSLog(@"%@",dic);
}