需要xcdatamodel吗？

Question

这是我的iOS应用程序中使用CoreData的实体对象。

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

#import "Price.h"

@interface DataPrice : NSManagedObject

@property (nonatomic) NSInteger id;
@property (nonatomic, retain) NSNumber *ron95;
@property (nonatomic, retain) NSNumber *ron92;
@property (nonatomic, retain) NSNumber *dieselNormal;
@property (nonatomic, retain) NSNumber *dieselSpecial;
@property (nonatomic, retain) NSDate *postDate;

+ (instancetype)insertDataPriceWithPrice:(Price*)price
                  inManagedObjectContext:(NSManagedObjectContext *)managedObjectContext;

+ (instancetype)fetchDataPriceInManagedObjectContext:(NSManagedObjectContext *)managedObjectContext;

+ (Price*)fetchPriceInManagedObjectContext:(NSManagedObjectContext *)managedObjectContext;

@end


#import "DataPrice.h"

@implementation DataPrice

@dynamic id;
@dynamic ron95;
@dynamic ron92;
@dynamic dieselNormal;
@dynamic dieselSpecial;
@dynamic postDate;

+ (instancetype)insertDataPriceWithPrice:(Price*)price
             inManagedObjectContext:(NSManagedObjectContext *)managedObjectContext
{
    DataPrice* dataPrice = [NSEntityDescription insertNewObjectForEntityForName:self.entityName
                                               inManagedObjectContext:managedObjectContext];
    dataPrice.id = price.id;
    dataPrice.ron95 = price.ron95;
    dataPrice.ron92 = price.ron92;
    dataPrice.dieselNormal = price.dieselNormal;
    dataPrice.dieselSpecial = price.dieselSpecial;
    dataPrice.postDate = price.postDate;

    return dataPrice;
}

+ (NSString*)entityName
{
    return @"Price";
}

+ (instancetype)fetchDataPriceInManagedObjectContext:(NSManagedObjectContext *)managedObjectContext {
    NSEntityDescription *entity = [NSEntityDescription entityForName:self.entityName inManagedObjectContext:managedObjectContext];

    if (!entity) {
        return NULL;
    }


    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"postDate" ascending:NO];

    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    request.entity = entity;
    request.sortDescriptors = @[ sortDescriptor ];
    request.fetchLimit = 1;

    NSError *error;
    NSArray *fetchResults = [managedObjectContext executeFetchRequest:request error:&error];

    DataPrice *result = fetchResults.firstObject;

    return result;
}

+ (Price*)fetchPriceInManagedObjectContext:(NSManagedObjectContext *)managedObjectContext {
    DataPrice *dataPrice = [self fetchDataPriceInManagedObjectContext:managedObjectContext];

    Price *price = [[Price alloc] init];
    price.id = dataPrice.id;
    price.ron92 = dataPrice.ron92;
    price.ron95 = dataPrice.ron95;
    price.dieselNormal = dataPrice.dieselNormal;
    price.dieselSpecial = dataPrice.dieselSpecial;
    price.postDate = dataPrice.postDate;

    return price;
}


@end

我将类命名为DataPrice，但希望实体为Price。

对于我的应用程序，我需要一个xcdatamodel吗?我如何定义一个？

Answer 1

是的，你需要一个数据模型。您可以通过File _ New…获得它文件和工作表中的iOS \ Core数据/数据模型。

但是，从一开始就更容易创建核心数据应用程序。

类和实体(类型)可以有不同的名称。您只需为实体类型分配一个具有不同名称的类。(为所有未被称为NSManagedObject的实体类型分配了一个不同的名称，默认为NSManagedObject。)但几乎没有理由这样做。