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

追寻最真