ios - 使用未声明的标识符核心数据

Question

我正在 Xcode 7 beta 6 中使用核心数据，我刚刚为每个实体生成了类别和托管对象子类。问题是，当我尝试利用模型中的属性创建的属性时，我收到“使用未声明的标识符”错误。我的印象是我应该将自定义行为放入生成的托管对象子类中，但是我不清楚如何使用托管对象子类中类别的属性，因此我将自定义行为放入类别如下所示。我觉得我只是错过了一个导入声明，但我不确定。我知道我正在使用测试版软件。

核心数据模型:

Thought+CoreDataProperties.h:

#import "Thought.h"

NS_ASSUME_NONNULL_BEGIN

@interface Thought (CoreDataProperties)

@property (nullable, nonatomic, retain) NSString *objectId;
@property (nullable, nonatomic, retain) id recordId;
@property (nullable, nonatomic, retain) Collection *parentCollection;

@property (nullable, nonatomic, retain) NSNumber *placement;

@property (nullable, nonatomic, retain) NSString *text;
@property (nullable, nonatomic, retain) NSString *extraText; // allows for extra description text to be set. Should be in smaller print than headline text and should only appear as an option in text != nil
@property (nullable, nonatomic, retain) NSSet<Photo *> *photos;
@property (nullable, nonatomic, retain) id location; // place a CLLocation here

@property (nullable, nonatomic, retain) id tags; // place an NSArray here

@property (nullable, nonatomic, retain) NSDate *creationDate;

#pragma mark - Initializers

/*!
 @abstract this method converts a CKRecord into a Thought object
 @discussion parentCollection will still be nil after this method executes
 */
-(nullable instancetype) initWithRecord: (nonnull CKRecord *) record;

/*!
 @abstract this method converts a CKRecord into a Thought object. photos set is not populated
 */
-(nullable instancetype)initWithRecord: (nonnull CKRecord *) record collection: (nonnull Collection *) collection;

/*!
 @abstract Creates a new Thought object with generic recordId, objectId, placement, and photos array
 @discussion parentCollection will still be nil after this method executes
 */
-(nullable instancetype) init;

   … other methods

@end

@interface Thought (CoreDataGeneratedAccessors)

- (void)addPhotosObject:(Photo *)value;
- (void)removePhotosObject:(Photo *)value;
- (void)addPhotos:(NSSet<Photo *> *)values;
- (void)removePhotos:(NSSet<Photo *> *)values;

@end

NS_ASSUME_NONNULL_END

Thought+CoreDataProperties.m:

#import "Thought+CoreDataProperties.h"

@implementation Thought (CoreDataProperties)

@dynamic creationDate;
@dynamic extraText;
@dynamic location;
@dynamic objectId;
@dynamic placement;
@dynamic recordId;
@dynamic tags;
@dynamic text;
@dynamic parentCollection;
@dynamic photos;

-(nullable instancetype) init {
    self = [super init];
    if (self) {

       // THIS IS WHERE I GET MANY ERROR FOR USE OF UNDECLARED IDENTIFIER
        _objectId = [IdentifierCreator createId];

        _recordId = [[CKRecord alloc] initWithRecordType:THOUGHT_RECORD_TYPE zoneID:[[CKRecordZone alloc] initWithZoneName:ZONE_NAME].zoneID].recordID;

        _photos = [NSArray new];

        _placement = [NSNumber numberWithInt:0];

        _creationDate = [NSDate date];
    }
    return self;
}

-(instancetype) initWithRecord:(nonnull CKRecord *)record {
    self = [super init];
    if (self) {
        _objectId = [record objectForKey:OBJECT_ID_KEY];

        _recordId = [record recordID];

        _text = [record objectForKey:TEXT_KEY];
        _extraText = [record objectForKey:EXTRA_TEXT_KEY];
        _location = [record objectForKey:LOCATION_KEY];

        _photos = [NSSet new];

        _tags = [record objectForKey:TAGS_KEY];

        _placement = [record objectForKey:PLACEMENT_KEY];
        _creationDate = record.creationDate;
    }
    return self;
}

-(instancetype) initWithRecord:(CKRecord *)record collection:(Collection *)collection {
    self = [self initWithRecord:record];
    self.parentCollection = collection;
    return self;
}

Thought.h:

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#import "Frameworks.h" // includes Frameworks I'm using and some string constants
#import "ForFundamentals.h" // includes mostly string constants
#import "Photo.h"
#import "Collection.h"

@class Collection, Photo;

NS_ASSUME_NONNULL_BEGIN

@interface Thought : NSManagedObject

// I think I should put method declarations here

@end

NS_ASSUME_NONNULL_END

#import "Thought+CoreDataProperties.h"

思想.m:

#import "Thought.h"
#import "Collection.h"
#import "Photo.h"

@implementation Thought

// I think I should put method implementations here

@end

Answer 1

NSManagedObject 的子类在 awakeFromInsert 或 awakeFromFetch 中进行初始化。不要覆盖 init 或实现 initWith...。您必须等到对象被实例化，并在 NSManagedObjectContext 中处于事件状态，然后才能设置其属性。

不要将集合实例分配给对应于 Core Data 关系(即 _photos、parentCollection)的 ivar。Core Data 会在您插入或获取对象。

代替您的 init 方法，重新考虑您的方法。编写方法 insertInManagedObjectContext:withSKRecord。该方法调用 -insertNewObjectForEntityForName:@"Thought"inManagedObjectContext:foo，返回 Thought 的实例。现在，有了那个 istance，设置 objecgtID、recordID 等——但是使用您的访问器，而不是直接敲打实例变量。