使用未聲明的標識符核心數據

Question

我在Xcode 7 beta 6中使用核心數據，並且爲每個實體生成類別和託管對象子類。問題是，當我嘗試利用從我的模型中的屬性創建的屬性時，出現「使用未聲明的標識符」錯誤。我的印象是，我應該把自定義行爲放在託管對象的子類中，但是我不清楚如何使用託管對象子類中的類別的屬性，所以我將自定義行爲放在類別如下所示。我覺得我只是錯過了一個導入聲明，但我不確定。我瞭解我正在使用測試版軟件。

核心數據模型：

思想+ 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 

思想+ 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" 

Thought.m：

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

@implementation Thought 

// I think I should put method implementations here 

@end 

Answer 1

NSManagedObject的子類在awakeFromInsert或awakeFromFetch中進行初始化。請勿覆蓋init或執行initWith...。您必須等到該對象被實例化並在NSManagedObjectContext之內生效，然後才能設置其屬性。

不要指定集合實例對應於核心數據的關係（即_photos，parentCollection。核心數據會爲你做的，當你插入或獲取對象。

，而不是你init方法，重新審視自己的ivars你的方法。，但等你的存取，而不是直接撞的實例變量寫一個方法insertInManagedObjectContext:withSKRecord。這個方法調用-insertNewObjectForEntityForName:@"Thought" inManagedObjectContext:foo，它返回的Thought一個實例。現在，與istance，設置objecgtID，的recordId。

Answer 2

如此看來，雖然我不能用_name = @"string"語法來設置屬性值，我可以使用方法語法，就像[self setName: @"string"]。這對我來說似乎很陌生。然而，該方法的語法在子類和類別都有效，所以我猜問題已經解決了......現在。

UPDATE

我不明白@dynamic。 post幫助清除它。我無法使用_propertyName，因爲訪問方法是由核心數據動態創建的。