0

:D 抱歉，我对此很陌生，我正试图围绕核心数据展开思考。我有两个视图控制器。第一个（称为 PVC）是一个表格视图控制器，有两个部分，其中包含用户输入的姓名和电子邮件。他们从该屏幕按添加，然后将他们带到第二个视图控制器（称为 PDVC），用户在其中添加姓名和电子邮件，并指定条目将属于哪个部分（受托人或收件人）。当他们在该屏幕上点击完成时，信息被保存到核心数据中，并将它们带回 PVC，核心数据在 PVC 中获取该信息并将其放入表视图中。

我想要完成的是，当用户点击从 PVC 发送时，我需要获取该信息（输入的每个名称和电子邮件）JSON，并将其发送到服务器。我用我想出的一个技巧成功地做到了这一点，它将每个项目存储到字典中，然后获取这些键/值对并将它们添加到一个可变数组中，所有这些都来自 PDVC。问题是，所有这些数据都需要像核心数据一样持久，因此使用核心数据来获取这些信息而不是我的hack是有意义的。我的问题是，这可能吗？我需要能够从核心数据中“提取”某些键值对。如果我能做到这一点，我相信我能解决剩下的问题。我了解您可以使用一种方法将核心数据信息存储到数组中，但它还附带我无法使用的其他信息：

array of fetched objects: (
"<Credentials: 0xb9c6ed0> (entity: Credentials; id: 0xb9bfa90 <x-coredata://BE51A026-9D1B-      4A93-BA34-4EAC55B8B9DF/Credentials/p1> ; data: {\n    category = Trustees;\n    name = aef;\n     settingsEmail = \"inawef@hioe.com\";\n})",
"<Credentials: 0xb9c6f40> (entity: Credentials; id: 0xb9c6ae0 <x-coredata://BE51A026-9D1B- 4A93-BA34-4EAC55B8B9DF/Credentials/p3> ; data: {\n    category = Trustees;\n    name = awef;\n     settingsEmail = \"waef@aioc.com\";\n})",
"<Credentials: 0xb9c6fc0> (entity: Credentials; id: 0xb9c6af0 <x-coredata://BE51A026-9D1B- 4A93-BA34-4EAC55B8B9DF/Credentials/p2> ;

我只需要从该信息中获取名称和 settingsEmail 键/值对。任何帮助将不胜感激！这是我的其余代码

PVC.h

@interface PeopleViewController : UITableViewController<NSFetchedResultsControllerDelegate>
{
NSMutableArray *listOfItems;
}
- (IBAction)doneButtonPressed:(id)sender;
- (IBAction)sendPressed:(id)sender;
@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;

@end

PVC.m

#import "PeopleViewController.h"
#import "AppDelegate.h"
#import "PeopleDetailViewController.h"
#import "Credentials.h"
#import "AlertLoad.h"
#import "Data.h"
#import "ASIFormDataRequest.h"


@interface PeopleViewController ()

@end

@implementation PeopleViewController
{
NSFetchedResultsController *fetchedResultsController;
AlertLoad *alertLoad;
Data *dataObj;

}
@synthesize managedObjectContext;


- (NSFetchedResultsController *)fetchedResultsController
{
if (fetchedResultsController == nil)
{

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription        entityForName:@"Credentials" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    NSSortDescriptor *sortDescriptor1 = [NSSortDescriptor   sortDescriptorWithKey:@"category" ascending:NO];
    NSSortDescriptor *sortDescriptor2 = [NSSortDescriptor  sortDescriptorWithKey:@"name" ascending:YES];
    [fetchRequest setSortDescriptors:[NSArray arrayWithObjects:sortDescriptor1,  sortDescriptor2, nil]];

    [fetchRequest setFetchBatchSize:20];

    fetchedResultsController = [[NSFetchedResultsController alloc]
                                initWithFetchRequest:fetchRequest
                                managedObjectContext:self.managedObjectContext
                                sectionNameKeyPath:@"category"
                                cacheName:@"Credentials"];

    fetchedResultsController.delegate = self;
}
return fetchedResultsController;
}

- (void)performFetch
{
NSError *error;
if (![self.fetchedResultsController performFetch:&error]) {
    FATAL_CORE_DATA_ERROR(error);
    return;
}
}

- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(@"view did load");
dataObj = [Data dataObj];
dataObj.trusteeArray = [[NSMutableArray alloc]init];
dataObj.recipientArray = [[NSMutableArray alloc]init];

    if (self.managedObjectContext == nil)
    {
        self.managedObjectContext = [(AppDelegate *) [[UIApplication sharedApplication]  delegate] managedObjectContext];
        NSLog(@"After managedObjectContext: %@",  self.managedObjectContext);
    }
[self performFetch];
NSLog(@"array of fetched objects: %@", [fetchedResultsController fetchedObjects]);
[self.navigationController setToolbarHidden:NO];


self.navigationItem.title = @"Swipe to delete";
}



 - (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
// Release anything that's not essential, such as cached data
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{

PeopleDetailViewController *controller = segue.destinationViewController;
controller.managedObjectContext = self.managedObjectContext;


}

#pragma mark Table view methods

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
//return [listOfItems count];
return [[self.fetchedResultsController sections] count];
}


// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections]   objectAtIndex:section];
return [sectionInfo numberOfObjects];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:  (NSInteger)section
{

id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController  sections] objectAtIndex:section];
return [sectionInfo name];

}

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{

Credentials *credentials = [self.fetchedResultsController objectAtIndexPath:indexPath];
if ([credentials.name length] > 0)
{
    cell.textLabel.text = credentials.name;
}
else
{
    cell.textLabel.text = @"(New Entry)";
}
if (credentials.settingsEmail != nil)
{
    cell.detailTextLabel.text = credentials.settingsEmail;
}
else
{
    cell.detailTextLabel.text = @"Tap to edit";
}
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:   (UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
    Credentials *credentials = [self.fetchedResultsController  objectAtIndexPath:indexPath];
    [self.managedObjectContext deleteObject:credentials];

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


// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath  *)indexPath
{

static NSString *CellIdentifier = @"Cell";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
                                   reuseIdentifier:CellIdentifier];
}
[self configureCell:cell atIndexPath:indexPath];
// Set up the cell...

return cell;
}


-(void)infoSent
{
[alertLoad close];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success" message:@"Your trustees and recipients have been submitted" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
[alert show];
[self dismissViewControllerAnimated:YES completion:nil];
}

-(void)sendDataWithString:(NSString *)string
{
NSURL *url = [NSURL URLWithString:@"http://lastwords.com.au/lastwords/"];

ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];

[request setPostValue:dataObj.username              forKey:@"author"];
[request setPostValue:dataObj.password              forKey:@"password"];
[request setPostValue:string                        forKey:@"participants"];
[request setPostValue:@"set_participants"           forKey:@"json"];
[request startSynchronous];

NSError *error = [request error];
if (error != nil)
{
    [alertLoad close];

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:error.localizedDescription delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
    [alert show];
    NSLog(@"error: %@", error);
}
else
{
    NSString *response = [request responseString];
    NSLog(@"response: %@", response);
    [self performSelectorOnMainThread:@selector(infoSent) withObject:nil waitUntilDone:YES];
}

}

- (IBAction)doneButtonPressed:(id)sender
{
[self.navigationController dismissViewControllerAnimated:YES completion:nil];
}

- (IBAction)sendPressed:(id)sender
{

if ([self.tableView numberOfRowsInSection:0] > 3)
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Too many trustees" message:@"You can only submit a maximum of 3 trustees." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
    [alert show];
}
else if ([self.tableView numberOfRowsInSection:0] < 3)
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Not enough trustees"  message:@"You must select 3 trustees." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
    [alert show];
}
else if ([self.tableView numberOfSections] < 2)
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No trustees or recipients" message:@"You must enter at least enter 3 trustees and at least one recipient." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
    [alert show];
}

else
{
    alertLoad = [[AlertLoad alloc]
                 initWithTitle:@"Submitting..."
                 message:@"Submitting your trustees and recipients. Please wait...\n\n\n"
                 delegate:self cancelButtonTitle:@"Cancel"
                 otherButtonTitles:nil];
    alertLoad.delegate = self;

    [alertLoad show];
    NSDictionary *dictionary = [NSDictionary  dictionaryWithObjectsAndKeys:dataObj.trusteeArray,@"trustees", dataObj.recipientArray,  @"recipients", nil];
    NSError *error;
    NSData* jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:kNilOptions error:&error];
    NSString* jSONString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    NSLog(@"json??: %@", jSONString);
    [self performSelectorInBackground:@selector(sendDataWithString:) withObject:jSONString];


}

}



@end

（取出获取结果委托的东西以节省空间）

PDVC.h

@interface PeopleDetailViewController : UIViewController<UITextFieldDelegate>
@property (weak, nonatomic) IBOutlet UITextField *txtFieldName;
@property (weak, nonatomic) IBOutlet UITextField *txtFieldEmail;
@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
@property (weak, nonatomic) IBOutlet UISegmentedControl *segment;
- (IBAction)done:(id)sender;
@end

PDVC.m

#import "PeopleDetailViewController.h"
#import "AppDelegate.h"
#import "Credentials.h"
#import "Data.h"

@interface PeopleDetailViewController ()

{
Data *dataObj;
}
@end

@implementation PeopleDetailViewController
@synthesize managedObjectContext;



- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(@"view did load");
dataObj = [Data dataObj];

if (self.managedObjectContext == nil)
{
    self.managedObjectContext = [(AppDelegate *) [[UIApplication sharedApplication] delegate] managedObjectContext];
    NSLog(@"After managedObjectContext: %@",  self.managedObjectContext);
}
// Uncomment the following line to preserve selection between presentations.
// self.clearsSelectionOnViewWillAppear = NO;

// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}


#pragma mark - textField Delegate
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
[textField resignFirstResponder];

return YES;
}



- (IBAction)done:(id)sender
{
NSString *emailRegEx = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegEx];

if (self.txtFieldEmail.text.length < 1 || self.txtFieldName.text.length < 1)
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

else if ([emailTest evaluateWithObject:self.txtFieldEmail.text] == NO)
{
    //Valid email addres
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Invalid email" message:@"Please enter a valid email address" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
        [alert show];
}

else
{
    Credentials *credentials = [NSEntityDescription insertNewObjectForEntityForName:@"Credentials" inManagedObjectContext:self.managedObjectContext];

    credentials.name = self.txtFieldName.text;
    credentials.settingsEmail = self.txtFieldEmail.text;

    if (self.segment.selectedSegmentIndex == 0)
    {
        credentials.category = @"Trustees";
        NSDictionary *trusteeDict = [NSDictionary dictionaryWithObjectsAndKeys:self.txtFieldName.text,@"name", self.txtFieldEmail.text,@"email", nil];
        NSError *error;
        NSData* jsonData = [NSJSONSerialization dataWithJSONObject:trusteeDict options:kNilOptions error:&error];
        NSString* jSONString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        NSLog(@"json??: %@", jSONString);
        [dataObj.trusteeArray addObject:trusteeDict];
        NSLog(@"trusteeArray: %@", dataObj.trusteeArray);

    }
    else
    {
        credentials.category = @"Recipients";
        NSDictionary *recipientDict = [NSDictionary dictionaryWithObjectsAndKeys:self.txtFieldName.text,@"name", self.txtFieldEmail.text,@"email", nil];
        NSError *error;
        NSData* jsonData = [NSJSONSerialization dataWithJSONObject:recipientDict options:kNilOptions error:&error];
        NSString* jSONString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        NSLog(@"json??: %@", jSONString);
        [dataObj.recipientArray addObject:recipientDict];
        NSLog(@"recipientArray: %@", dataObj.recipientArray);
    }

    NSError *error;
    if (![self.managedObjectContext save:&error])
    {
    FATAL_CORE_DATA_ERROR(error);
    return;
    }
        [self dismissViewControllerAnimated:YES completion:nil];
}
}


@end
4

1 回答 1

0

您的问题有点令人困惑，但您可以使用 2 种非常简单的方法从核心数据中获取特定信息。

1）像这样在提取中使用谓词

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"User"
                                              inManagedObjectContext:self.managedObjectContext];
    fetchRequest.entity = entity;
    fetchRequest.predicate = [NSPredicate predicateWithFormat:@"userID = %@", userIDYouAreLookingfor];

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

    NSLog(@"%@",fetchedObjects);

2) 父关系在 NSSet 中指定其实体，您可以测试它们以检索某些对象：

NSSet *picturesResult = [_thumbnailsStorage.pictures objectsPassingTest:^BOOL(id obj, BOOL *stop) {
        Picture *pic = obj;
        // Check for a condition here
        if (someCondition) {
            return YES;
        }
        return NO;
    }];

如果这不是您所要求的，请告诉我，看看我是否可以提供帮助。

于 2012-11-21T01:16:36.450 回答