1

运行我的应用程序时，我不断收到此错误：“CoreData：错误：无法在 NSManagedObject 类“Ambulance”上调用指定的初始化程序”。我已经在堆栈溢出上看到了这个问题，但我不确定如何在我的情况下实施解决方案。有任何想法吗？

救护车.h

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


@interface Ambulance : NSManagedObject

@property (nonatomic, retain) NSString * ambulanceID;
@property (nonatomic, retain) NSNumber * distance;
@property (nonatomic, retain) NSNumber * etaDistance;
@property (nonatomic, retain) NSString * emsID;
@property (nonatomic, retain) NSString * lat;
@property (nonatomic, retain) NSString * lng;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSNumber * occupancy;
@property (nonatomic, retain) NSString * type;
@property (nonatomic, retain) NSString * websocketServer;
@property (nonatomic, retain) NSNumber * seconds;
@property (nonatomic, retain) id eta;

+(Ambulance *)nearestAmbulanceByType:(NSString *)type;


- (id)initWithCoder:(NSCoder *)decoder;
- (void)encodeWithCoder:(NSCoder *)encoder;


@end

救护车.m

#import "Ambulance.h"


@implementation Ambulance

@synthesize ambulanceID;
@synthesize distance;
@synthesize etaDistance;
@synthesize emsID;
@synthesize lat;
@synthesize lng;
@synthesize name;
@synthesize occupancy;
@synthesize type;
@synthesize websocketServer;
@synthesize seconds;
@synthesize eta;


+(Ambulance *)nearestAmbulanceByType:(NSString *)type {
NSArray *sortedArray = [Ambulance findByAttribute:@"type" withValue:type         andOrderBy:@"distance" ascending:YES];
return [sortedArray first];
 }


  - (void)encodeWithCoder:(NSCoder *)encoder {
//Encode properties, other class variables, etc
[encoder encodeObject:self.ambulanceID forKey:@"ambulanceID"];
[encoder encodeObject:self.distance forKey:@"distance"];
[encoder encodeObject:self.etaDistance forKey:@"etaDistance"];
[encoder encodeObject:self.emsID forKey:@"emsID"];
[encoder encodeObject:self.lat forKey:@"lat"];
[encoder encodeObject:self.lng forKey:@"lng"];
[encoder encodeObject:self.name forKey:@"name"];
[encoder encodeObject:self.occupancy forKey:@"occupancy"];
[encoder encodeObject:self.type forKey:@"type"];
[encoder encodeObject:self.websocketServer:@"websocketServer"];
[encoder encodeObject:self.seconds forKey:@"seconds"];
[encoder encodeObject:self.eta forKey:@"eta"];

}

- (id)initWithCoder:(NSCoder *)decoder {


if((self = [super init])) {
    //decode properties, other class vars


    self.ambulanceID = [decoder decodeObjectForKey:@"ambulanceID"];
    self.distance = [decoder decodeObjectForKey:@"distance"];
    self.etaDistance = [decoder decodeObjectForKey:@"etaDistance"];
    self.emsID = [decoder decodeObjectForKey:@"emsID"];
    self.lat = [decoder decodeObjectForKey:@"lat"];
    self.lng = [decoder decodeObjectForKey:@"lng"];
    self.name = [decoder decodeObjectForKey:@"name"];
    self.occupancy = [decoder decodeObjectForKey:@"occupancy"];
    self.type = [decoder decodeObjectForKey:@"type"];
    self.websocketServer = [decoder decodeObjectForKey:@"websocketServer"];
    self.seconds = [decoder decodeObjectForKey:@"seconds"];
    self.eta = [decoder decodeObjectForKey:@"eta"];

}
return self;
}
4

2 回答 2

1

initWithEntity:insertIntoManagedObjectContext:您应该使用除子类之外的任何其他初始化程序NSManagedObject。

从文档：

重要提示：此方法是 NSManagedObject 的指定初始化程序。您不能简单地通过发送 init 来初始化托管对象。

你确定你必须在你的子类中使用 NSCoding 吗？存储 objectID 可能就足够了，因为您的对象存在于 NSManagedObjectContext 中并且可能无论如何都会被持久化。

如果你真的依赖 NSCoding，你必须确定并将正确的 NSManagedObjectContext 提供给initWithEntity:insertIntoManagedObjectContext:in initWithCoder:。

于 2013-06-27T18:13:10.477 回答
0

不确定这与 RestKit 有什么关系，以及为什么您认为需要支持编码。

假设您使用的是 RestKit，您应该能够更改为：

- (id)initWithCoder:(NSCoder *)decoder {
    NSManagedObjectContext *moc = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Ambulance" inManagedObjectContext:moc];

    if((self = [super initWithEntity:entity insertIntoManagedObjectContext:moc])) {
    ...

如果您不使用 RestKit，那么您将需要一种不同的方式来获取 MOC。

于 2013-06-27T19:01:31.757 回答