NSDictionary 字典 & KVC 的使用

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字典分为不可变字典(NSDictionary)和可变字典(NSMutableDictionary)

/* 不可变字典 */

1.创建字典

        NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:                             @"male",@"sex",                             @"20", @"age",                             @"Tom", @"name",                             @"run", @"hobby", nil];

2.获取所有的key值和value值

        [dic allKeys];        [dic allValues];

3.根据key值来获取value值

        [dic valueForKey:@"name"];

       [dic objectForKey:@"name"];

// 写法2 不可以写 nil, 写法1可以

4.遍历字典

        NSArray *arr = [dic allKeys];        for (int i = 0; i < [arr count]; i++) {            NSString *key = [arr objectAtIndex:i];            [dic objectForKey:key];        }

        for (NSString *key in dic) {           NSString *value = [dic objectForKey:key];        }

//写法2虽然写的是遍历字典,实际上还是遍历数组[dic allKeys];

/* 可变字典 */

1. 创建可变字典

        NSMutableDictionary *mDic = [NSMutableDictionary dictionaryWithObjectsAndKeys:                                     @"male",@"sex",                                     @"20", @"age",nil];

2.增加键值对

        [mDic setValue:@"Tom" forKey:@"name"];        [mDic setObject:@"Running" forKey:@"hobby"];

3.修改键值对

       [mDic setValue:@"18" forKey:@"age"];

//跟2.增加键值对方法是一样的, 这个key值要是有就覆盖掉原来的value, 如果没有这个key值就相当于新添加一对键值对

4.删除键值对

       [mDic removeObjectForKey:@"age"];               [mDic setValue:nil forKey:@"age"];

/*model 类 */

OC中继承于 NSObject 的这些类统称 model 类 (用于存取字符串)

model类更像可变字典

例题1 把下列格式的输出用字典-数组嵌套的形式写出, 并转成model类的形式

(

{

body = {

"message" ="错误信息";

"errorcode" ="1";

};

header = (

{

"page" =@"10";

"title" =@"婚纱";

"content" =@"fwefasd";

"image" = (

@"http://www.hunliji.com1",

@"http://www.hunliji.com2",

@"http://www.hunliji.com3"

);

}

);

}

)

[1]字典-数组嵌套

        NSMutableArray *bigArray = [NSMutableArray array];                NSMutableDictionary *bigDic = [NSMutableDictionary dictionary];        [bigArray addObject:bigDic];                NSMutableDictionary *bodyDic = [NSMutableDictionary dictionary];        [bodyDic setObject:@"错误信息" forKey:@"message"];        [bodyDic setObject:@"1" forKey:@"errorcode"];        [bigDic setObject:bodyDic forKey:@"body"];                        NSMutableArray *headerArray = [NSMutableArray array];        [bigDic setObject:headerArray forKey:@"header"];                NSMutableDictionary *little = [NSMutableDictionary dictionary];        [headerArray addObject:little];                [little setObject:@"10" forKey:@"page"];        [little setObject:@"婚纱" forKey:@"title"];        [little setObject:@"fwefasd" forKey:@"content"];                        NSMutableArray *images = [NSMutableArray array];        [images addObject:@"http://www.hunliji.com1"];        [images addObject:@"http://www.hunliji.com2"];        [images addObject:@"http://www.hunliji.com3"];        [little setObject:images forKey:@"image"];

[2] model类的形式

//建立model类要从结构里往外建立

1.建立HeaderModel

@interface HeaderModel : NSObject{    @public    NSString *_page;    NSString *_title;    NSString *_content;    NSMutableArray *_imageArray;}

2.建立BodyModel

@interface BodyModel : NSObject{    @public    NSString *_message;    NSString *_errorcode;}

3.建立BigModel

@class BodyModel;@interface BigModel : NSObject{    @public    BodyModel *_body;    NSMutableArray *_headerArray; // 数组中存headermodel对象}</span>

4.建立了一个工具类Tools将功能进行封装

<span style="font-size:18px;">@class BigModel;@interface Tools : NSObject+ (BigModel *)getBigModel;

#import "Tools.h"#import "BigModel.h"#import "BodyModel.h"#import "HeaderModel.h"@implementation Tools+ (BigModel *)getBigModel{    BigModel *big = [[BigModel alloc] init];    big->_body = [[BodyModel alloc] init];    big->_body->_message = @"错误信息";    big->_body->_errorcode = @"10";        big->_headerArray = [NSMutableArray array];        HeaderModel *header = [[HeaderModel alloc] init];    [big->_headerArray addObject:header];        header->_content = @"fjaowief";    header->_imageArray = [NSMutableArray array];    [header->_imageArray addObject:@"http://www.hunliji.com1"];    [header->_imageArray addObject:@"http://www.hunliji.com1"];    [header->_imageArray addObject:@"http://www.hunliji.com1"];        header->_page = @"10";    header->_title = @"婚纱";        return big;}+ (NSString *)getValueFrom:(NSMutableArray *)array key:(NSString *)content{    BigModel *b = [array firstObject];    HeaderModel *header = [b->_headerArray firstObject];        NSString *my = header->_content;    return my;}

main.m

    NSMutableArray *bigArray = [NSMutableArray array];    BigModel *b1 = [Tools getBigModel];    [bigArray addObject:b1];    BigModel *b2 = [Tools getBigModel];    [bigArray addObject:b2];

/*KVC */

key - value - coding

1. 给属性赋值:

    [dic setValue:<#(id)#> forKey:<#(NSString *)#>];

2. 最大的用处: 字典和model 的转换

3.通过字典给model 赋值:

<span style="font-size:14px;">    [model setValuesForKeysWithDictionary:<#(NSDictionary *)#>];</span>

必须在model类里重写:

<span style="font-size:14px;">-(void)setValue:(id)value forKey:(NSString *)key</span>

空着就可以, 如果没有定义这个属性, 就什么都不用写

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