只有在消息中的文本被更改时才能保存核心数据？ Xcode中

Question

所以在Xcode中，我有一个利用核心数据的笔记应用程序。有两个字段，标题文本字段和消息文本视图。我遇到的一个问题是，如果用户做出注释并决定稍后进行编辑，则用户必须编辑该消息以使其能够再次保存。无论我是否更改消息或标题，我都希望它保存。感谢

   #import "DeviceDetailViewController.h"
@interface DeviceDetailViewController ()

@end

@implementation DeviceDetailViewController
@synthesize device;
- (NSManagedObjectContext *)managedObjectContext {
    NSManagedObjectContext *context = nil;
    id delegate = [[UIApplication sharedApplication] delegate];
    if ([delegate performSelector:@selector(managedObjectContext)]) {
        context = [delegate managedObjectContext];
    }
    return context;
}
@synthesize message;
@synthesize titles;
@synthesize button;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [button setEnabled:NO];
    titles.delegate = self;
    message.delegate = (id)self;
    // Do any additional setup after loading the view.
    if (self.device) {
        [self.titles setText:[self.device valueForKey:@"name"]];
        [self.message setText:[self.device valueForKey:@"version"]];
    }

}

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

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

- (IBAction)save:(id)sender {
    NSManagedObjectContext *context = [self managedObjectContext];
    if (self.device) {
        // Update existing device
        [self.device setValue:self.titles.text forKey:@"name"];
        [self.device setValue:self.message.text forKey:@"version"];

    } else {
        // Create a new device
        NSManagedObject *newDevice = [NSEntityDescription insertNewObjectForEntityForName:@"Device" inManagedObjectContext:context];
        [newDevice setValue:self.titles.text forKey:@"name"];
        [newDevice setValue:self.message.text forKey:@"version"];
        }

    NSError *error = nil;
    // Save the object to persistent store
    if (![context save:&error]) {
        NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]);
        }

    [self dismissViewControllerAnimated:YES completion:nil];
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range     replacementString:(NSString *)string
{
    if (titles.text.length >= 35 && range.length == 0)
        return NO;
        return YES;
}
//Code beyond this point is disabling keyboard when you click outside of textfield
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [message resignFirstResponder];
    [titles resignFirstResponder];
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [titles resignFirstResponder];
    return NO;
}
//Enabling/disabling 'Save' button based on texfield data
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
        if ([titles.text length] != 0 && [message.text length] != 0)    {

            [button setEnabled:YES];
    }
    else

    {
            [button setEnabled:NO];
    }

    return YES;
}
@end