import＆＃34; TripLog.h＆＃34;顶部的文字

Question

您好我是iOS中核心数据的新手，我已经实现了4个文本字段，即姓名，年龄，公司，地址。现在，当用户输入数据时，我将数据保存在Core Data中。

NSManagedObjectContext *context =
[appDelegate managedObjectContext];

NSManagedObject *newContact;
newContact = [NSEntityDescription
              insertNewObjectForEntityForName:@"Device"
              inManagedObjectContext:context];
[newContact setValue: _name.text forKey:@"name"];
[newContact setValue: _address.text forKey:@"address"];
[newContact setValue: _age.text forKey:@"age"];
[newContact setValue:_company.text forKey:@"company

同样，我可以在这些文本字段中获取和显示数据。

AppDelegate * appDelegate = [[UIApplication sharedApplication]委托];

NSManagedObjectContext *context =
[appDelegate managedObjectContext];

NSEntityDescription *entityDesc =
[NSEntityDescription entityForName:@"Device"
            inManagedObjectContext:context];

NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDesc];

NSPredicate *pred =
[NSPredicate predicateWithFormat:@"(name = %@)",
 _name.text];
[request setPredicate:pred];
NSManagedObject *matches = nil;

NSError *error;
NSArray *objects = [context executeFetchRequest:request
                                          error:&error];matches = objects[0];

    _address.text = [matches valueForKey:@"address"];
    _age.text = [matches valueForKey:@"age"];
    _company.text = [matches valueForKey:@"company"];

现在，当我想删除和更新特定用户的数据时，我无法获取数据。

如何删除数据并更新..？

我已经通过了这个链接 http://www.appcoda.com/core-data-tutorial-update-delete/

先谢谢

Answer 1

您可以删除以下数据：

 NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"entityname" inManagedObjectContext:context];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"userID like %@",userID];
    [fetchRequest setEntity:entity];
    [fetchRequest setPredicate:predicate];

    NSError *error;
    NSArray *items = [context executeFetchRequest:fetchRequest error:&error];

    for (NSManagedObject *managedObject in items)
    {
        [context deleteObject:managedObject];
    }

和更新：

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"entityname" inManagedObjectContext:context];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"userID like %@",userID];
    [fetchRequest setPredicate:predicate];
    [fetchRequest setFetchLimit:1];
    [fetchRequest setEntity:entity];
    NSError *error;
    NSArray *arrResult = [context executeFetchRequest:fetchRequest error:&error];
YourEntityname *entity = arrResult[0];
entity.userID = @"2"
[appdelegate saveContext];

Answer 2

首先更新NSManagedObject，你需要从fetch数组获取对象并更改该对象的值并再次保存

NSError *error;              
if (![[self managedObjectContext] save:&error]) {

     NSLog(@"%@",[error1 localizedDescription]);

}
else
{
     NSLog(@"save Successfully");               
}

删除

[[self managedObjectContext] deleteObject:<#(nonnull NSManagedObject *)#>]

传递您要删除的NSManage对象

斯威夫特3： -

创建记录。

具有两个属性名称，数字的人物实体。

let person = NSEntityDescription.insertNewObject(forEntityName: "Person", into: manageObjectContext) as! Person
person.name = "<#name string#>"
person.number = "<#number string#>"
do {
   try manageObjectContext.save()
}
catch {
   print(error.localizedDescription)
}

获取记录

  var Per = [Person]()

  let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Person")
  do {
      Per = try manageObjectContext().fetch(fetchRequest) as! [Person]
  } catch {
      print(error.localizedDescription)
  }

更新记录

ler person = per[0] 
person.name = "<#name string#>"
person.number = "<#number string#>"
do {
   try manageObjectContext.save()
}
catch {
   print(error.localizedDescription)
}

删除记录：

let person = per[0]

self.manageObjectContext().delete(person)

do {
     try manageObjectContext().save()
}
catch {
     print(error.localizedDescription)
}

Answer 3

要删除核心数据中的对象，您可以使用以下代码：传递您要删除的实体名称......

-(void)deleteAllObjects: (NSString *)entityName{
    NSFetchRequest *request=[NSFetchRequest fetchRequestWithEntityName:entityName];
    NSError *error;
    NSArray *items =[self.managedObjectContext executeFetchRequest:request error:&error];

    for (NSManagedObject *managedObject in items) {
        [self.managedObjectContext deleteObject:managedObject];
    }
    if(![self.managedObjectContext save:&error]){
        NSLog(@"Error deleting: %@ - error: %@",entityName,error);
    }
}

Answer 4

首先，您已创建具有属性的实体。
示例TripLog是一个实体，属性是date，startLat，startLong，endLat，endLatitude。
创建NSManagement文件TripLog。 h和TripLog。米

TripLog.h包含@property的变量声明。 TripLog.m包含变量的实现。
为TripLog创建类别文件（添加）。

创建NSObject文件以对selectData，updateData，DeleteData。

进行操作

实体文件：代码快照 TripLog.h

@interface TripLog : NSManagedObject

@property (nullable, nonatomic, retain) NSString *date;
@property (nullable, nonatomic, retain) NSString *startLatitude;
@property (nullable, nonatomic, retain) NSString *startLongitude;
@property (nullable, nonatomic, retain) NSString *endLatitude;
@property (nullable, nonatomic, retain) NSString *endLongitude;
@property (nullable, nonatomic, retain) NSNumber *distance;
@end

TripLog.m

@implementation TripLog

@dynamic date;
@dynamic startLatitude;
@dynamic startLongitude;
@dynamic endLatitude;
@dynamic endLongitude;
@dynamic distance;

@end

类别文件：代码Snap

TripLog + Addition.h

#import "TripLog.h"

@interface TripLog (Addition)

+ (TripLog *)indexWithDictionary:(NSDictionary *)dict inManagedObjectContext:(NSManagedObjectContext *)context;

@end

TripLog + Addition.m

#import "TripLog+Addition.h"

@implementation TripLog (Addition)


+ (TripLog *)indexWithDictionary:(NSDictionary *)dict inManagedObjectContext:(NSManagedObjectContext *)context
{
TripLog *indexValues      = [NSEntityDescription insertNewObjectForEntityForName:@"TripLog"
                                                               inManagedObjectContext:context];

indexValues.date      = [dict valueForKey:@"date"];
indexValues.startLatitude   = [dict valueForKey:@"startLatitude"];
indexValues.startLongitude  = [dict valueForKey:@"startLongitude"];
indexValues.endLatitude     = [dict valueForKey:@"endLatitude"];
indexValues.endLongitude    = [dict valueForKey:@"endLongitude"];
indexValues.distance        = [NSNumber numberWithDouble:[[dict valueForKey:@"distance"]doubleValue]];



return indexValues;
}
@end

NSObjectFile：DataManager

 #import "TripLog.h"

 @protocol DataManagerDelegate;
 @interface DataManager : NSObject{

 }
 @property (nonatomic, strong) UIManagedDocument *dataDocument;
 @property (nonatomic, assign) id <DataManagerDelegate> delegate;
 @property (nonatomic, strong) TripLog *tripLog;
 @property (nonatomic, retain, readonly) NSManagedObjectModel   * managedObjectModel;
 @property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
 @property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;
 + (DataManager *)sharedInstance;
 -(void)saveTripLogDetails:(NSDictionary *)tripLogDict;
 - (void)updateTripLog:(NSDictionary *)tripLogDict;
 - (void)deleteTripLog:(id)object;
 -(NSArray *)getTripLogDetails;
 @end
 @protocol DataManagerDelegate <NSObject>
 @optional
 - (void)didFinishSaving:(DataManager *)dataManager;
 @end

Datamanager.m文件

#import "DataManager.h" 
#import "AppDelegate.h"
#import "TripLog+Addition.h"

@interface DataManager ()

 - (void)contextDidSave:(NSNotification *)notification;
@end

@implementation DataManager

@synthesize dataDocument;
@synthesize delegate;

@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

#pragma mark - SharedInstance

+ (DataManager *)sharedInstance
 {
  static DataManager *sharedInstance = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    sharedInstance = [[DataManager alloc] init];
  });
  return sharedInstance;
 }

  - (id)init {
   self = [super init];

   if (self) {

    // Initialise the classe
    // Create the Core Data document
    NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory
                                                         inDomains:NSUserDomainMask] lastObject];
    url = [url URLByAppendingPathComponent:@"Gridz.sqlite"];

    self.dataDocument = [[UIManagedDocument alloc] initWithFileURL:url];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *filePath =  [documentsDirectory stringByAppendingPathComponent:@"Gridz.sqlite"];


    if([[NSFileManager defaultManager] fileExistsAtPath:filePath]){
        [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
    }



    // Set our document up for automatic migrations
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                             [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
    self.dataDocument.persistentStoreOptions = options;

    [self setupDocument];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(contextDidSave:)
                                                 name:NSManagedObjectContextDidSaveNotification
                                               object:self.dataDocument.managedObjectContext];


}
return self;
}



 - (NSString *)applicationDocumentsDirectory {
 return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
 }


 #pragma mark - Context Notification Methods

 - (void)objectsDidChange:(NSNotification *)notification
 {
  NSLog(@"NSManagedObjects did change.");

  [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(contextDidSave:)
                                             name:NSManagedObjectContextDidSaveNotification
                                           object:self.dataDocument.managedObjectContext];

 }

 - (void)contextDidSave:(NSNotification *)notification
 {
 NSlog(@"NSManagedContext did save.");

 [[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:NSManagedObjectContextDidSaveNotification
                                              object:self.dataDocument.managedObjectContext];

if ([delegate respondsToSelector:@selector(didFinishSaving:)]) {
    [delegate didFinishSaving:self];
}
}
#pragma mark - Setup Document

- (void)setupDocument {

if (![[NSFileManager defaultManager] fileExistsAtPath:[self.dataDocument.fileURL path]]) {
LOG(@"does not exist on disk, so create it");
// does not exist on disk, so create it
[self.dataDocument saveToURL:self.dataDocument.fileURL
            forSaveOperation:UIDocumentSaveForCreating
           completionHandler:^(BOOL success) {

           }];
} else if (self.dataDocument.documentState == UIDocumentStateClosed) {
LOG(@"exists on disk, but we need to open it");
// exists on disk, but we need to open it
[self.dataDocument openWithCompletionHandler:^(BOOL success) {

}];
} else if (self.dataDocument.documentState == UIDocumentStateNormal) {
LOG(@"UIDocumentStateNormal");
}
}
-(void)saveTripLogDetails:(NSDictionary *)tripLogDict
{
self.tripLog =[TripLog indexWithDictionary:tripLogDict inManagedObjectContext:self.dataDocument.managedObjectContext];

}
- (void)deleteTripLog:(id)object {
 if (object)
 {
  [self.dataDocument. managedObjectContext deleteObject: indexObject];
        }
 }
   -(NSArray *)getTripLogDetails{
   NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
   NSEntityDescription *entity  = [NSEntityDescription entityForName:@"TripLog"
                                       inManagedObjectContext:self.dataDocument.managedObjectContext];
   NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"distance" ascending:YES];

  fetchRequest.sortDescriptors = [NSArray arrayWithObject:sortDescriptor];

  [fetchRequest setEntity:entity];
  NSError *error = nil;
  NSArray *fetchedObjects = [self.dataDocument.managedObjectContext executeFetchRequest:fetchRequest error:&error];
   return fetchedObjects;
 }    

  -(void)updateTripLog :(NSMutableDictionary *)dict
 {

   NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
   NSEntityDescription *entity  = [NSEntityDescription entityForName:@"TripLog"
                                       inManagedObjectContext:self.dataDocument.managedObjectContext];

    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"date" ascending:YES];

    fetchRequest.predicate = [NSPredicate predicateWithFormat:@"((date== %@))",[dict valueForKey:@"date"]];
    fetchRequest.sortDescriptors = [NSArray arrayWithObject:sortDescriptor];

    [fetchRequest setEntity:entity];

     NSError *error = nil;
     NSArray *fetchedObjects =    [self.dataDocument.managedObjectContext executeFetchRequest:fetchRequest error:&error];

    if([fetchedObjects count]>0){
    TripLog *indexValues = [fetchedObjects objectAtIndex:0];

    indexValues.date      = [dict valueForKey:@"date"];
    indexValues.startLatitude   = [dict valueForKey:@"startLatitude"];
    indexValues.startLongitude  = [dict valueForKey:@"startLongitude"];
    indexValues.endLatitude     = [dict valueForKey:@"endLatitude"];
    indexValues.endLongitude    = [dict valueForKey:@"endLongitude"];
    indexValues.distance        = [NSNumber numberWithDouble:[[dict valueForKey:@"distance"]doubleValue]];


}else
   [self saveTripLogDetails:dict]; //insert Dictionary
 }

@end

使用Viewcontroller中的DataManger文件

import＆＃34; TripLog.h＆＃34;顶部的文字

在viewDidLoad

中

 NSArray *tripDetails = [[DataManager sharedInstance] getTripDetails];
 TripLog *tribLog = [tripDetails objectAtIndex:0];
 NSLog(@"TripDate:%@",tribLog.date);
 [[DataManager sharedInstance]deleteTripDetails:tribLog]; //delete the tripDetails

Answer 5

 func Update(name: String , address : String , mobile : String , email : String , imgs : NSString) {

    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
        return
    }

    let managedContext = appDelegate.persistentContainer.viewContext
    let entity = NSEntityDescription.entity(forEntityName: "Person", in: managedContext)!
     //let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "entity")

    let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "Person")

        do {
            let array_users = try managedContext.fetch(fetchRequest)
            let people = array_users[0] as NSManagedObject

            //let person = NSManagedObject(entity: entity, insertInto: managedContext)

            people.setValue(name, forKeyPath: "name")
            people.setValue(address, forKeyPath: "address")
            people.setValue(imgs, forKeyPath: "img")
            people.setValue(email, forKeyPath: "mailid")
            people.setValue(mobile, forKeyPath: "mobile")                //save the context
            do {
                try managedContext.save()
                print("saved!")
            } catch let error as NSError  {
                print("Could not save \(error), \(error.userInfo)")
            } catch {

            }

        } catch {
            print("Error with request: \(error)")
        }
  }

在iOS中删除和更新Core Data中的数据

5 个答案:

import＆＃34; TripLog.h＆＃34;顶部的文字