所以我有一个实用程序应用程序，我试图将一些文本保存到翻转视图控制器上的“收件人”和“消息：文本字段。但是，我的数据不会保存。我是目标 C 的新手，我一直是使用多个不同的教程到我完全困惑自己的地步。希望你能帮助我。不知道此时还能做什么......
FlipsideViewController.m
#import "CCCFlipsideViewController.h"
#import "CCCAppDelegate.h"
#import "CCCMainViewController.h"
#import "MessageDetails.h"
@interface CCCFlipsideViewController ()
{
// NSManagedObjectContext *context;
}
@end
@implementation CCCFlipsideViewController
@synthesize allMessageDetails;
@synthesize managedObjectContext;
- (void)awakeFromNib
{
[super awakeFromNib];
CCCAppDelegate *appDelegateController = [[CCCAppDelegate alloc]init];
self.managedObjectContext = appDelegateController.managedObjectContext;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:@"MessageDetails" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSError *error;
self.allMessageDetails = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
/*
NSManagedObject *managedObject; = [_fetchedResultsController valueForKey:@"to"];
self.toTextField.text = managedObject to;
messageDetails.to = [allMessageDetails firstObject];
self.toTextField.text = messageDetails.to;
messageDetails.message = [allMessageDetails valueForKey:@"message"];
self.messageTextField.text = messageDetails.message;
*/
NSLog(@"The 'to' is currently at %@ after viewdidload", self.toTextField.text);
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
return [textField resignFirstResponder]; //function says that if (bool) the text field is open and the keyboard hits return, text field is to resign first responder.
}
#pragma mark - Actions
- (IBAction)done:(id)sender
{
[self.delegate flipsideViewControllerDidFinish:self];
}
- (IBAction)resignFirstResponder:(id)sender {
[self.toTextField resignFirstResponder];
[self.messageTextField resignFirstResponder];
NSLog(@"Resigned First Responder");
}
- (IBAction)save:(id)sender {
// Create a new instance of the entity managed by the fetched results controller.
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
// If appropriate, configure the new managed object.
[newManagedObject setValue:self.toTextField.text forKey:@"to"];
[newManagedObject setValue:self.messageTextField.text forKey:@"message"];
// Save the context.
NSError *error = nil;
if (![context save:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
*/
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
#pragma mark -
#pragma mark Fetched results controller
- (NSFetchedResultsController *)fetchedResultsController {
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
/*
Set up the fetched results controller.
*/
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"MessageDetails" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"to" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"Root"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
NSError *error = nil;
if (![_fetchedResultsController performFetch:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
*/
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _fetchedResultsController;
}
@end