MJExtension

长话短说下面我们通过一个列子来看下怎么使用

1、 先把框架拉进去你的项目

2、 首先我这次用到的json最外层是一个字典，根据数据的模型我们可以把这个归类为字典中有数组，数组中还有其他 针对于这种情况 我需要建立两个数据模型 一个是要获取其中的数组 另一个数组中的的City元素

                                                        代码后面讲解思路

#import <Foundation/Foundation.h>

@interface NSCity : NSObject

@property (nonatomic,strong)NSString *city;

@property (nonatomic,strong)NSString *h5_url;

@property (nonatomic,strong)NSNumber* ID;

@property (nonatomic,strong)NSString *deal_url;

@end

//  NSCity.m

//  MJExtension example

//

//  Created by tareba on 15/12/18.

//  Copyright © 2015年 tanada. All rights reserved.

//

#import "NSCity.h"

@implementation NSCity

- (void)setValue:(id)value forUndefinedKey:(NSString *)key {

    if ([key isEqualToString:@"id"]) {

        self.ID=value;

    }

}

@end

#import <Foundation/Foundation.h>

@interface NSDeals : NSObject

@property (nonatomic,strong)NSMutableArray *deals;

@end

#import "NSDeals.h"

#import "MJExtension.h"

@implementation NSDeals

下面的方法是关键

+ (NSDictionary *)mj_objectClassInArray

{

    return @{

             @"deals" : @"NSCity",

             };

}

@end

#import "ViewController.h"

#import "MJExtension.h"

#import "NSCity.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    NSURLRequest *request =[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://api.dianping.com/v1/deal/find_deals?appkey=4123794720&category=%E7%BE%8E%E9%A3%9F&city=%E9%83%91%E5%B7%9E&region=%E9%87%91%E6%B0%B4%E5%8C%BA&sort=2&sign=FB7A61EB742A4B697B666985348614C7A8F763A3"]];

    NSURLSession *seesion = [NSURLSession sharedSession];

    NSURLSessionDataTask *task =[seesion dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {

        NSDictionary *dic= [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

        NSDeals *result =[NSDeals mj_objectWithKeyValues:dic];

        for (NSCity *city in result.deals) {

            NSLog(@"%lu",(unsigned long)result.deals.count);

            NSLog(@"%@",city.deal_url);

        }

    }];

    [task resume];

}

@end

这个方法是将json数据的层级关系，变成属性关系，下一层成为了上一层的属性，然后通过属性直接姐可以访问了。至于关键字成为属性，由于时间紧迫未来的及验证是否和平时利用 setvaluefor undefinekey的法解决是否相同 待验证后会尽快修改