【iOS】JSONModel的基本使用

---

前言

JSONModel 是一个用于 Objective-C 的开源库，它用于简化 JSON 数据与 iOS 应用中的数据模型之间的转换。

其最主要的优点就是简化 JSON 数据解析与减少模型代码的编写，JSONModel可以将json数据直接映射到我们的对象中，对于我们获取的数据更加方便。同时对于模型的嵌套数据的获取更加便捷。

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一、导入JSONModel

这里笔者在先前的博客中已经讲的很详细，不再赘述，详见【iOS】Cocoapods的安装以及使用

---

二、JSONModel的基本使用

单单讲解JSONModel理论知识过于抽象，笔者将会给出例子来对JSONModel进行讲解，JSONModel请求的网络数据的API如下：API

通过上图我们可以看到我们的Json数据共有三个字段，这三个字段就可以成为我们JSONModel类中的属性

1.基本用法

我们首先创建一个继承于JSONModel的TestModel，然后将字段作为该类中的属性

#import "JSONModel.h"
#import "Manager.h"
NS_ASSUME_NONNULL_BEGIN

//{
//    "status":1,
//    "msg":"【更新内容】\r\n\r\n★ 多图有标记 流量壕忽略\r\n★ 出门前离线 没网也能看\r\n★ 喜欢请好评 不喜快吐槽\r\n★ 萌妹工程师 邮箱在下面\r\[email protected]\r\n（一般人我们不告诉他）",
//    "latest":"2.5"
//}

@interface TestModel : JSONModel

@property (nonatomic, assign) int status;
@property (nonatomic, copy) NSString *msg;
@property (nonatomic, copy) NSString *latest;

@end

NS_ASSUME_NONNULL_END

然后我们在进行网络请求时将我们请求到的数据导入到我们的Model中

    [manager GET:url parameters:nil headers:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        TestModel *testModel = [[TestModel alloc] initWithDictionary:responseObject error:nil];
        NSLog(@"%@", testModel);
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        NSLog(@"Error: %@", error);
    }];

然后我们打印的到了如下数据

---

2.模型集合

但是如果对于我们的Json数据中有着key的嵌套，那么就会这样输出就会出现一些问题

例如此时我们请求的json数据如下：

{
    "date":"20231018",
    "stories":[
        {
            "image_hue":"0xb3a27d",
            "title":"长平之战，廉颇主张防守，是对是错？",
            "url":"https:\/\/daily.zhihu.com\/story\/9766453",
            "hint":"众人皆醒我独醉 · 7 分钟阅读",
            "ga_prefix":"101807",
            "images":[
                "https:\/\/picx.zhimg.com\/v2-e3db2cb91bb097c111072487caf70737.jpg?source=8673f162"
            ],
            "type":0,
            "id":9766453
        },
        {
            "image_hue":"0x6d502d",
            "title":"不用化肥，如何让没有肥力的土地快速变得有肥？",
            "url":"https:\/\/daily.zhihu.com\/story\/9766437",
            "hint":"刘文龙PhD · 5 分钟阅读",
            "ga_prefix":"101807",
            "images":[
                "https:\/\/picx.zhimg.com\/v2-709e63e4a8870b25887454f4f587234b.jpg?source=8673f162"
            ],
            "type":0,
            "id":9766437
        },
        {
            "image_hue":"0x7c5b26",
            "title":"瞎扯 · 如何正确地吐槽",
            "url":"https:\/\/daily.zhihu.com\/story\/9766461",
            "hint":"VOL.3215",
            "ga_prefix":"101806",
            "images":[
                "https:\/\/picx.zhimg.com\/v2-924083b893973c3ae7d12b9c11155d8d.jpg?source=8673f162"
            ],
            "type":0,
            "id":9766461
        }
    ],
    "top_stories":[
        {
            "image_hue":"0xb3a27d",
            "hint":"作者 \/ 众人皆醒我独醉",
            "url":"https:\/\/daily.zhihu.com\/story\/9766453",
            "image":"https:\/\/picx.zhimg.com\/v2-b3b010976682ab3b7ba240c318e3cf9b.jpg?source=8673f162",
            "title":"长平之战，廉颇主张防守，是对是错？",
            "ga_prefix":"101807",
            "type":0,
            "id":9766453
        },
        {
            "image_hue":"0xb37229",
            "hint":"作者 \/ 匿名用户",
            "url":"https:\/\/daily.zhihu.com\/story\/9766426",
            "image":"https:\/\/pic1.zhimg.com\/v2-15928648a5270b506392f48a7eee2d8c.jpg?source=8673f162",
            "title":"你曾经被哪些自己所学专业的鬼畜知识震惊过？",
            "ga_prefix":"101707",
            "type":0,
            "id":9766426
        },
        {
            "image_hue":"0x3b3045",
            "hint":"作者 \/ 单长殷",
            "url":"https:\/\/daily.zhihu.com\/story\/9766350",
            "image":"https:\/\/pic1.zhimg.com\/v2-52190997fe05a0af480a2ae26c3775a9.jpg?source=8673f162",
            "title":"小事 · 哪些时刻让你体会到「知识的实用与浪漫」？",
            "ga_prefix":"101407",
            "type":0,
            "id":9766350
        }
    ]
}

Model属性如下：

//声明网络请求中要接受数据的两个协议
@protocol StoriesModel
@end

@protocol Top_StoriesModel
@end

#import "JSONModel.h"

NS_ASSUME_NONNULL_BEGIN

@interface StoriesModel : JSONModel
@property (nonatomic, copy) NSString* image_hue;
@property (nonatomic, copy) NSString* title;
@property (nonatomic, copy) NSString* url;
@property (nonatomic, copy) NSString* hint;
@property (nonatomic, copy) NSString* ga_prefix;
@property (nonatomic, copy) NSString* type;
@property (nonatomic, copy) NSString* id;

@end

@interface Top_StoriesModel : JSONModel
@property (nonatomic, copy) NSString* image_hue;
@property (nonatomic, copy) NSString* hint;
@property (nonatomic, copy) NSString* url;
@property (nonatomic, copy) NSString* title;
@property (nonatomic, copy) NSString* ga_prefix;
@property (nonatomic, copy) NSString* type;
@property (nonatomic, copy) NSString* id;

@end

@interface TestModel3 : JSONModel
@property (nonatomic, copy) NSString *date;//三个同类型的
@property (nonatomic, copy) NSArray<StoriesModel>* stories;
@property (nonatomic, copy) NSArray<Top_StoriesModel>* top_stories;

@end

NS_ASSUME_NONNULL_END

注意：NSArray后的<>包含一个协议。这与OC泛型系统不同。它们不是相互排斥的，但是对于JSONModel来说，协议必须到位。

此时我们仍然直接打印我们的Model

    [manager GET:url parameters:nil headers:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        
        TestModel3 *testModel = [[TestModel3 alloc] initWithDictionary:responseObject error:nil];
        NSLog(@"%@", testModel);
        mainModelBolck(testModel);
        
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        NSLog(@"Error: %@", error);
    }];

出现如下结果：

<TestModel3> 
   [date]: 20231018
   [stories]: (
       " \n   [image_hue]: 0xb3a27d\n   [ga_prefix]: 101807\n   [id]: 9766453\n   [title]: \U957f\U5e73\U4e4b\U6218\Uff0c\U5ec9\U9887\U4e3b\U5f20\U9632\U5b88\Uff0c\U662f\U5bf9\U662f\U9519\Uff1f\n   [hint]: \U4f17\U4eba\U7686\U9192\U6211\U72ec\U9189 \U00b7 7 \U5206\U949f\U9605\U8bfb\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766453\n",
       " \n   [image_hue]: 0x6d502d\n   [ga_prefix]: 101807\n   [id]: 9766437\n   [title]: \U4e0d\U7528\U5316\U80a5\Uff0c\U5982\U4f55\U8ba9\U6ca1\U6709\U80a5\U529b\U7684\U571f\U5730\U5feb\U901f\U53d8\U5f97\U6709\U80a5\Uff1f\n   [hint]: \U5218\U6587\U9f99PhD \U00b7 5 \U5206\U949f\U9605\U8bfb\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766437\n",
       " \n   [image_hue]: 0x40312d\n   [ga_prefix]: 101807\n   [id]: 9766445\n   [title]: \U5982\U679c\U6c38\U751f\U4eba\U7c7b\U7ec6\U80de\U300c\U6d77\U62c9\U7ec6\U80de\U300d\U6cc4\U9732\U4e86\U4f1a\U6709\U5371\U9669\U5417\Uff1f\n   [hint]: \U567c\U91cc\U556a\U5566\U7830 \U00b7 1 \U5206\U949f\U9605\U8bfb\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766445\n",
       " \n   [image_hue]: 0x6d9c95\n   [ga_prefix]: 101807\n   [id]: 9766457\n   [title]: \U5fae\U8f6f\U7b97\U6cd5\U9762\U8bd5\U9898\U300c\U5224\U65ad\U9ebb\U5c06\U662f\U5426\U548c\U724c\U300d\U5e94\U8be5\U5982\U4f55\U505a\Uff1f\n   [hint]: \U8001\U987d\U7ae5 \U00b7 22 \U5206\U949f\U9605\U8bfb\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766457\n",
       " \n   [image_hue]: 0x7c5b26\n   [ga_prefix]: 101806\n   [id]: 9766461\n   [title]: \U778e\U626f \U00b7 \U5982\U4f55\U6b63\U786e\U5730\U5410\U69fd\n   [hint]: VOL.3215\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766461\n"
   )
   [top_stories]: (
       " \n   [image_hue]: 0xb3a27d\n   [ga_prefix]: 101807\n   [id]: 9766453\n   [title]: \U957f\U5e73\U4e4b\U6218\Uff0c\U5ec9\U9887\U4e3b\U5f20\U9632\U5b88\Uff0c\U662f\U5bf9\U662f\U9519\Uff1f\n   [hint]: \U4f5c\U8005 / \U4f17\U4eba\U7686\U9192\U6211\U72ec\U9189\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766453\n",
       " \n   [image_hue]: 0xb37229\n   [ga_prefix]: 101707\n   [id]: 9766426\n   [title]: \U4f60\U66fe\U7ecf\U88ab\U54ea\U4e9b\U81ea\U5df1\U6240\U5b66\U4e13\U4e1a\U7684\U9b3c\U755c\U77e5\U8bc6\U9707\U60ca\U8fc7\Uff1f\n   [hint]: \U4f5c\U8005 / \U533f\U540d\U7528\U6237\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766426\n",
       " \n   [image_hue]: 0x2e6889\n   [ga_prefix]: 101607\n   [id]: 9766400\n   [title]: \U4e3a\U4ec0\U4e48\U6709\U300c\U597d\U5403\U300d\U7684\U8bf4\U6cd5\Uff0c\U6ca1\U6709\U300c\U574f\U5403\U300d\U7684\U8bf4\U6cd5\Uff1f\n   [hint]: \U4f5c\U8005 / \U591a\U90bb\U56fdDuolingo\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766400\n",
       " \n   [image_hue]: 0x8f8164\n   [ga_prefix]: 101507\n   [id]: 9766378\n   [title]: \U5c0f\U4e8b \U00b7 \U6709\U54ea\U4e9b\U8ba9\U4f60\U5fc3\U9178\U7684\U6545\U4e8b\Uff1f\n   [hint]: \U4f5c\U8005 / \U9ec4\U4e0d\U4f1a\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766378\n",
       " \n   [image_hue]: 0x3b3045\n   [ga_prefix]: 101407\n   [id]: 9766350\n   [title]: \U5c0f\U4e8b \U00b7 \U54ea\U4e9b\U65f6\U523b\U8ba9\U4f60\U4f53\U4f1a\U5230\U300c\U77e5\U8bc6\U7684\U5b9e\U7528\U4e0e\U6d6a\U6f2b\U300d\Uff1f\n   [hint]: \U4f5c\U8005 / \U5355\U957f\U6bb7\n   [type]: 0\n   [url]: https://daily.zhihu.com/story/9766350\n"
   )
</TestModel3>

因为我们的StoriesModel与Top_StoriesModel属于是被TestModel3嵌套的Model，因此我们直接打印TestModel3的对象时stories与top_stories中的数据时打印得到的是其并未转换为NSString的数据，而是Unicode 转义序列的字符串

如果我们想要得到里面的对象转换为字符串的数据，我们需要事先声明一个嵌套的Model属性

@property (nonatomic, copy)StoriesModel *t;

然后将大Model中的数组赋值给小Model

	TestModel3 *testModel = [[TestModel3 alloc] initWithDictionary:responseObject error:nil];
	self.t = testModel.stories[0];
	NSLog(@"%@", self.t);

打印得到：

我们的testModel中的两个NSArray中的对象类型是两个协议，这两个协议的作用是定义了数据模型的接口规范，以便 JSONModel
库知道如何将 JSON 数据映射到具体的对象。通过采用这种方式，可以更灵活地定义数据模型对象，适应不同类型的数据，并在解析 JSON
数据时保持一致性。这使得你可以更容易地将 JSON 数据映射到相应的数据模型对象，以便在应用中使用这些数据。

---

3.模型导出为NSDictionary或JSON

ProductModel *pm = [ProductModel new];
pm.name = @"Some Name";

// convert to dictionary
NSDictionary *dict = [pm toDictionary];

// convert to json
NSString *string = [pm toJSONString];

---

4.设置所有属性可选（所有属性值可以为空）

设置所有属性可选的意义在于即使我们解析Json数据时即使返回为空也不会导致程序崩溃

@implementation TestModel3
+ (BOOL)propertyIsOptional:(NSString *)propertyName {
    return YES;
}
@end

@implementation StoriesModel
+ (BOOL)propertyIsOptional:(NSString *)propertyName {
    return YES;
}
@end

@implementation Top_StoriesModel
+ (BOOL)propertyIsOptional:(NSString *)propertyName {
    return YES;
}

@end

但是官方建议尽量避免使用该方法(即使要全部属性为可选，也尽量是在每个属性那里标注为Optional)

@property (nonatomic, strong) NSString<Optional>* optionalProperty;

---

5.下划线(蛇式)转驼峰命名法

{
    "order_id": 104,
    "order_product": "Product #1",
    "order_price": 12.95
}

@interface OrderModel : JSONModel
@property (nonatomic) NSInteger orderId;
@property (nonatomic) NSString *orderProduct;
@property (nonatomic) float orderPrice;
@end

@implementation OrderModel

+ (JSONKeyMapper *)keyMapper
{
    return [JSONKeyMapper mapperFromUnderscoreCaseToCamelCase];
}

@end