添加新的 initWithDictionary ：方法订单：

- (instancetype)initWithDictionary:(NSDictionary*)dictionary {
    if (self = [super init]) {
        self.OrderId = dictionary[@"OrderId"];
        self.Title = dictionary[@"Title"];
        self.Weight = dictionary[@"Weight"];    
    }
    return self;    
}

不要忘记添加 initWithDictionary 签名到 Order.h 文件

Don't forget to add initWithDictionary's signature to Order.h file

在获得JSON的方法中：

In the method where you get JSON:

NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *e;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:jsonData options:nil error:&e];
Order *order = [[Order alloc] initWithDictionary:dict];