Question

我的核心数据中有一个名为Weather的实体，格式如下：

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

@interface WeatherModel : NSManagedObject

@property (nonatomic, retain) NSString * cityName;
@property (nonatomic, retain) NSNumber * latitude;
@property (nonatomic, retain) NSNumber * longitude;
@property (nonatomic, retain) NSNumber * temperature;
@property (nonatomic, retain) NSNumber * humidity;
@property (nonatomic, retain) NSNumber * windSpeed;
@property (nonatomic, retain) NSNumber * rain;
@property (nonatomic, retain) NSDate * date;
@property (nonatomic, retain) NSString * iconId;
@property (nonatomic, retain) NSString * units;

@end

我将此模型的实例保存到Core Data，如下所示：

WeatherModel *bookmarkWeatherModel = (WeatherModel*)[DatabaseHelper insertNewEntityWithName:@"Weather" andContext:self.weatherManagedObjectContext];

[bookmarkWeatherModel setLatitude:[NSNumber numberWithDouble:0.0]];
[bookmarkWeatherModel setLongitude:[NSNumber numberWithDouble:0.0]];
[bookmarkWeatherModel setCityName:@"CityA"];
NSLog(@"%@", bookmarkWeatherModel.cityName);
NSLog(@"%@", bookmarkWeatherModel.latitude);

[DatabaseHelper saveCoreData:self.weatherManagedObjectContext];

但是每当我尝试访问任何NSNumber属性时（甚至在调用saveCoreData方法之后）， I get this error.

DatabaseHelper中的insertNewEntityWithName方法：

+ (NSManagedObject *)insertNewEntityWithName:(NSString *)entityName
                                  andContext:(NSManagedObjectContext *)managedObjectContext {
    NSManagedObject *entity = [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:managedObjectContext];
    return entity;
}

我尝试访问模型中的每个属性，只有抛出此错误的属性属于NSNumber类型。其他人工作得很好。

Answer 1

显然问题是我手工编写了模型的代码。我通过自动生成代码解决了这个问题。我通过在xcdatamodel中选择我的实体，在数据模型检查器中填写类名（WeatherModel）和Codegen（手动/无），然后选择编辑器＆gt;创建NSManagedObject子类来实现这一点。

尝试访问Core Data Model的NSNumber属性会产生EXC_BAD_ACCESS

1 个答案: