iOS中JSONModel的使用

基本使用

涉想你的JSON數據像這樣:

{ "id": "10", "country": "Germany", "dialCode": 49, "isInEurope": true }

• 爲你的數據模型建立一個Objective-C的類，繼承自JSONModel.
• 將JSON中的keys在.h文件中聲明爲屬性:

#import "JSONModel.h"

@interface CountryModel : JSONModel

@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString* country;
@property (strong, nonatomic) NSString* dialCode;
@property (assign, nonatomic) BOOL isInEurope;

@end

在.m文件中不須要作任何事情.

• 用數據初始化你的model:

#import "CountryModel.h"
...

NSString* json = (fetch here JSON from Internet) ...
NSError* err = nil;
CountryModel* country = [[CountryModel alloc] initWithString:json error:&err];

舉個例子

命名自動匹配

{
  "id": "123",
  "name": "Product name",
  "price": 12.95
}

@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString* name;
@property (assign, nonatomic) float price;
@end

@implementation ProductModel
@end

模型嵌套 (模型包含其餘模型)

{
  "order_id": 104,
  "total_price": 13.45,
  "product" : {
    "id": "123",
    "name": "Product name",
    "price": 12.95
  }
}

@interface OrderModel : JSONModel
@property (assign, nonatomic) int order_id;
@property (assign, nonatomic) float total_price;
@property (strong, nonatomic) ProductModel* product;
@end

@implementation OrderModel
@end

模型集合

{
  "order_id": 104,
  "total_price": 103.45,
  "products" : [
    {
      "id": "123",
      "name": "Product #1",
      "price": 12.95
    },
    {
      "id": "137",
      "name": "Product #2",
      "price": 82.95
    }
  ]
}

@protocol ProductModel
@end
@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString* name;
@property (assign, nonatomic) float price;
@end

@implementation ProductModel
@end

@interface OrderModel : JSONModel
@property (assign, nonatomic) int order_id;
@property (assign, nonatomic) float total_price;
@property (strong, nonatomic) NSArray<ProductModel>* products;
@end

@implementation OrderModel
@end

注意: 尖括號後 NSArray 包含一個協議. 這跟Objective-C原生的泛型不是一個概念. 他們不會衝突, 但對於JSONModel來講,協議必須在一個地方聲明.

key映射

{
  "order_id": 104,
  "order_details" : [
    {
      "name": "Product#1",
      "price": {
        "usd": 12.95
      }
    }
  ]
}

@interface OrderModel : JSONModel
@property (assign, nonatomic) int id;
@property (assign, nonatomic) float price;
@property (strong, nonatomic) NSString* productName;
@end

@implementation OrderModel

+(JSONKeyMapper*)keyMapper
{
  return [[JSONKeyMapper alloc] initWithDictionary:@{
    @"order_id": @"id",
    @"order_details.name": @"productName",
    @"order_details.price.usd": @"price"
  }];
}

@end

設置全局鍵映射(應用於全部model)

[JSONModel setGlobalKeyMapper:[
    [JSONKeyMapper alloc] initWithDictionary:@{
      @"item_id":@"ID",
      @"item.name": @"itemName"
   }]
];

設置下劃線自動轉駝峯

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

@interface OrderModel : JSONModel

@property (assign, nonatomic) int orderId;
@property (assign, nonatomic) float orderPrice;
@property (strong, nonatomic) NSString* orderProduct;

@end

@implementation OrderModel

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

@end

可選屬性 (就是說這個屬性能夠爲null或者爲空)

{
  "id": "123",
  "name": null,
  "price": 12.95
}

@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString<Optional>* name;
@property (assign, nonatomic) float price;
@property (strong, nonatomic) NSNumber<Optional>* uuid;
@end

@implementation ProductModel
@end

忽略屬性 (就是徹底忽略這個屬性)

{
  "id": "123",
  "name": null
}


@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString<Ignore>* customProperty;
@end

@implementation ProductModel
@end

設置全部的屬性爲可選(全部屬性值能夠爲空)

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

使用JSONModel自帶的 HTTP 請求

//add extra headers
[[JSONHTTPClient requestHeaders] setValue:@"MySecret" forKey:@"AuthorizationToken"];

//make post, get requests
[JSONHTTPClient postJSONFromURLWithString:@"http://mydomain.com/api"
                                   params:@{@"postParam1":@"value1"}
                               completion:^(id json, JSONModelError *err) {

                                   //check err, process json ...

                               }];

將model轉化爲字典或者json格式的字符串

ProductModel* pm = [[ProductModel alloc] initWithString:jsonString error:nil];
pm.name = @"Changed Name";

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

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

自定義數據的轉換

@implementation JSONValueTransformer (CustomTransformer)

- (NSDate *)NSDateFromNSString:(NSString*)string {
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:APIDateFormat];
    return [formatter dateFromString:string];
}

- (NSString *)JSONObjectFromNSDate:(NSDate *)date {
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:APIDateFormat];
    return [formatter stringFromDate:date];
}

@end

自定義處理指定的屬性

@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString* name;
@property (assign, nonatomic) float price;
@property (strong, nonatomic) NSLocale *locale;
@end

@implementation ProductModel

// Convert and assign the locale property
- (void)setLocaleWithNSString:(NSString*)string {
    self.locale = [NSLocale localeWithLocaleIdentifier:string];
}

- (NSString *)JSONObjectForLocale {
    return self.locale.localeIdentifier;
}

@end

自定義JSON校驗

@interface ProductModel : JSONModel
@property (assign, nonatomic) int id;
@property (strong, nonatomic) NSString* name;
@property (assign, nonatomic) float price;
@property (strong, nonatomic) NSLocale *locale;
@property (strong, nonatomic) NSNumber <Ignore> *minNameLength;
@end

@implementation ProductModel

- (BOOL)validate:(NSError *__autoreleasing *)error {
    BOOL valid = [super validate:error];

    if (self.name.length < self.minNameLength.integerValue) {
        *error = [NSError errorWithDomain:@"me.mycompany.com" code:1 userInfo:nil];
        valid = NO;
    }

    return valid;
}

@end