Object-C 学习笔记(十七)---Foundation之Dictionary

Dictonary
是由一个key-value来组成,key必须唯一,key是字符串对象,也可以是任意类型对象,value也是对象,字典里存放也必须是对象.

Dictonary跟Array的操作一样,分为不可变字典NSDictionary 与 可变字典 NSMutableDictonary.

常用操作看例子:

//
//  main.m
//  Foundation-Dictonary
//
//  Created by 5016 on 13-12-11.
//  Copyright (c) 2013年 dradon. All rights reserved.
//

#import <Foundation/Foundation.h>

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

@autoreleasepool {
//不可变字典:NSDictonary 是由一个key-value来组成,key必须唯一,key是字符串对象,也可以是任意类型对象,value也是对象,字典里存放也必须是对象
//1.以一个元素初始化
NSDictionary *dic1 = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:23] forKey:@"k1"];
NSLog(@"dic1 = %@",dic1);

//2.以多个元素初始化
NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"value1",@"k1",@"value2",@"k2", @"value3",@"k3",@"value4",@"k4",@"value5",@"k5",nil];
NSLog(@"dic2 = %@",dic2);

//3.以已有的字典中初始化一个字典
NSDictionary *dic3 = [NSDictionary dictionaryWithDictionary:dic1];
NSLog(@"dic3 = %@",dic3);

//4.获取字典的数量
NSInteger count = [dic2 count];
NSLog(@"dic2的键值对有:%ld个",count);

//5.获取某个key下得value
NSString *str = [dic2 objectForKey:@"k3"];
NSLog(@"str = %@",str);

//6.获取字典的所有key和value
NSArray *keyArray = [dic2 allKeys];
NSArray *valueArray = [dic2 allValues];
NSLog(@"keyArray=%@",keyArray);
NSLog(@"valueArray = %@",valueArray);

//7.利用key数组和value数组去初始化字典
NSArray *vArray=@[@"v1",@"v2",@"v3"];
NSArray *kArray=@[@"k1",@"k2",@"k3"];
NSDictionary *dic4 = [NSDictionary dictionaryWithObjects:vArray forKeys:kArray];
NSLog(@"%@",dic4);

/******************NSMutableDictionary***********************/
//8.利用不可变字典去初始化可变字典
NSMutableDictionary *mdic = [[NSMutableDictionary alloc] initWithDictionary:dic2];
NSLog(@"midc = %@",mdic);

//9.向可变字典追加整个字典
[mdic addEntriesFromDictionary:dic1];
NSLog(@"midc = %@",mdic);

//10.追加新键值对
[mdic setValue:@"dragon-yeah" forKey:@"myName"];
NSLog(@"midc = %@",mdic);

//11.初始化一个空可变字典
NSMutableDictionary *mdic1 = [NSMutableDictionary dictionary];
[mdic1 setDictionary:dic2];//添加字典
NSLog(@"midc1 = %@",mdic1);

//12,.根据key来删除字典对象
[mdic removeObjectForKey:@"k3"];
NSLog(@"midc = %@",mdic);

//13.根据某个key数组来删除字典元素
NSArray *keys =@[@"k2",@"k4"];
[mdic1 removeObjectsForKeys:keys];
NSLog(@"midc1 = %@",mdic1);

//14.移除所有的对象
[mdic1 removeAllObjects];
NSLog(@"midc1 = %@",mdic1);

//15.遍历字典
NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"value1",@"k1",@"value2",@"k2", @"value3",@"k3",@"value4",@"k4",@"value5",@"k5",nil];
//常规方法
NSArray *keys1 = [dic allKeys];
NSInteger length = [keys1 count];
for (int i = 0; i< length; i++) {
id key = [keys1 objectAtIndex:i];//遍历出key
id obj = [dic objectForKey:key];//遍历出value
NSLog(@"元素:%@",obj);
}
//快速枚举
for (id key in mdic) {
NSLog(@"key-values:%@",[mdic objectForKey:key]);
}
}
return 0;
}