常用的几个方法

json转模型

+ (instancetype)yy_modelWithJSON:(id)json;

模型转字符串

- (NSString *)yy_modelToJSONString 

字典转模型

+ (instancetype)yy_modelWithDictionary:(NSDictionary *)dictionary ;

声明数组、字典或者集合里的元素类型时要重写

+ (nullable NSDictionary<NSString *, id> *)modelContainerPropertyGenericClass；

例子：

# YYAlbum.h
@property (nonatomic, copy) NSString *name;
@property (nonatomic, strong) NSArray *photos; # Array<YYPhoto>
@property (nonatomic, strong) NSDictionary *likedUsers; # Key:name(NSString) Value:user(YYUser)
@property (nonatomic, strong) NSSet *likedUserIds; # Set<NSNumber>

# YYPhoto.h
@property (nonatomic, copy) NSString *url;
@property (nonatomic, copy) NSString *desc;

# YYAlbum.m
#把数组里面带有对象的类型专门按照这个方法，这个格式写出来
-(nullable NSDictionary<NSString *, id> *)modelContainerPropertyGenericClass{
    return @{
             @"photos"       : YYPhoto.class,
             @"likedUsers"   : YYUser.class,
             @"likedUserIds" : NSNumber.class
             };
}

字典里的key值与模型的属性值不一致要重置

+ (nullable NSDictionary<NSString *, id> *)modelCustomPropertyMapper;

事例：

# YYMessage.h
@property (nonatomic, assign) uint64_t messageId;
@property (nonatomic, strong) NSString *content;
@property (nonatomic, strong) NSDate *time;

# YYMessage.m
/*!
 *  1.该方法是 `字典里的属性Key` 和 `要转化为模型里的属性名` 不一样 而重写的
 *  前：模型的属性   后：字典里的属性
 */

+ (nullable NSDictionary<NSString *, id> *)modelCustomPropertyMapper{

    return @{@"messageId":@"i",
             @"content":@"c",
             @"time":@"t"};
}

/*!
 *  2. 下面的两个方法 `字典里值`与`模型的值`类型不一样`需要转换`而重写的方法
 *   NSDate *time     dic[@"t"]是double类型的的秒数
 */

/// Dic -> model
- (BOOL)modelCustomTransformFromDictionary:(NSDictionary *)dic {

    self.time = (NSDate *)[NSDate dateWithTimeIntervalSince1970:[dic[@"t"] doubleValue]/1000];

    return YES;
}

/// model -> Dic
- (BOOL)modelCustomTransformToDictionary:(NSMutableDictionary *)dic {

    dic[@"t"] = @([self.time timeIntervalSince1970] * 1000).description;

    return YES;
}

下面两者是属性值在两个dic与模型之间的转化方法

- (BOOL)modelCustomTransformFromDictionary:(NSDictionary *)dic ；
- (BOOL)modelCustomTransformToDictionary:(NSMutableDictionary *)dic；