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;}