删除存储为核心数据实体属性的图像

Question

我有一个名为CollectedLeaf的核心数据实体。

@interface CollectedLeaf :  NSManagedObject <LeafletRecognitionRequestDelegate>
{
    id <CollectedLeafDelegate> delegate_;
}

@property (nonatomic, assign) id <CollectedLeafDelegate> delegate;
@property (nonatomic, retain) NSString* leafID;
@property (nonatomic, retain) NSString* selectedSpecies;
@property (nonatomic, retain) NSString* latitude;
@property (nonatomic, retain) NSString* longitude;
@property (nonatomic, retain) NSString* altitude;
@property (nonatomic, retain) NSDate* collectedDate;
@property (nonatomic, retain) NSData * localImage;
@property (nonatomic, retain) LeafletURL* originalImageURL;
@property (nonatomic, retain) LeafletURL* segmentedImageURL;
@property (nonatomic, retain) Species* selectedSpeciesRel;
@property (nonatomic, retain) NSNumber* syncStatus;
@property (nonatomic, retain) NSDate* lastModified;
@property (nonatomic, retain) NSNumber* uploaded;
@property (nonatomic, retain) NSString* userDataset;
@property (nonatomic, retain) NSSet* CandidateSpecies;

如果没有互联网连接，我会将UIImagePickerController拍摄的图像转换为NSData并存储到我的核心数据中。

if (_internetReachability == NotReachable){
//Internet Connection Not Available

    if(imageToUpload){
    //They just tried to upload photo
    self.originalImageView.image = [UIImage imageWithData:imageToUpload];

    /*Save photo to core data here*/
    NSManagedObjectContext* context = self.collectedLeaf.managedObjectContext;
    collectedLeaf.localImage = imageToUpload;
    NSError* error;
    [context save:&error];
    }

只要有互联网连接，我就会将图像上传到服务器。但我知道在本地保存图像会占用大量内存，所以我想删除本地图像（只是分配给属性的值，而不是整个对象）。我可以用collectedLeaf.localImage = nil删除图像吗？

Answer 1

您可以将localImage设置为nil来删除图像。

// Upload the image to server

collectedLeaf.localImage = nil;

NSError* error;
[context save:&error];