need to fix error in code "Property 'managedObjectContext' not found on object of type 'id'."

Question

Im writing this code for my class and I'm stuck, the error is "Property 'managedObjectContext' not found on object of type 'id'

it falls on this line of code:

if (![self.detailItem.managedObjectContext save:&error]) 

I understand that earlier in the code I am setting newDetailItem to type id? :

- (void)setDetailItem:(id)newDetailItem
{
    if (_detailItem != newDetailItem) {
        _detailItem = newDetailItem;

        // Update the view.
        [self configureView];
    }

    if (self.masterPopoverController != nil) {
        [self.masterPopoverController dismissPopoverAnimated:YES];
    }        
}

here is the full code i have going right now:

#import "cavDetailViewController.h"


@interface cavDetailViewController ()
<UIAlertViewDelegate, UIActionSheetDelegate>
{
    UIAlertView *message;
}

@property (strong, nonatomic) UIPopoverController *masterPopoverController;
- (void)configureView;
@end

@implementation cavDetailViewController

#pragma mark - Managing the detail item

- (void)setDetailItem:(id)newDetailItem
{
    if (_detailItem != newDetailItem) {
        _detailItem = newDetailItem;

        // Update the view.
        [self configureView];
    }

    if (self.masterPopoverController != nil) {
        [self.masterPopoverController dismissPopoverAnimated:YES];
    }        
}

- (void)configureView
{
    // Update the user interface for the detail item.

    if (self.detailItem) {
        self.detailDescriptionLabel.text = [[self.detailItem valueForKey:@"timeStamp"] description];
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self configureView];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (IBAction)hideKeyboard:(id) sender
{
    [self.lattitude resignFirstResponder];
    [self.longitude resignFirstResponder];
    [self.description resignFirstResponder];
}

- (void) viewWillDisappear:(BOOL) pAnimated {
    [super viewWillDisappear:pAnimated];

    [self.detailItem setValue:self.lattitude.text    forKey:@"Lattitude"];
    [self.detailItem setValue:self.longitude.text    forKey:@"Longitude"];
    [self.detailItem setValue:self.description.text    forKey:@"Description"];

    NSNumber * v = [NSNumber numberWithDouble:[self.lattitude.text doubleValue]];
    NSNumber * v1 = [NSNumber numberWithDouble:[self.longitude.text doubleValue]];


    [self.detailItem setValue:v forKey:@"Lattitude"];
    [self.detailItem setValue:v1 forKey:@"Longitude"];

    // ND: do the update - ala master view code
    NSError *error = nil;
    if (![self.detailItem.managedObjectContext 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.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }


} // end method veiwWillDisappear

#pragma mark - Split view

- (void)splitViewController:(UISplitViewController *)splitController willHideViewController:(UIViewController *)viewController withBarButtonItem:(UIBarButtonItem *)barButtonItem forPopoverController:(UIPopoverController *)popoverController
{
    barButtonItem.title = NSLocalizedString(@"Master", @"Master");
    [self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
    self.masterPopoverController = popoverController;
}

- (void)splitViewController:(UISplitViewController *)splitController willShowViewController:(UIViewController *)viewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem
{
    // Called when the view is shown again in the split view, invalidating the button and popover controller.
    [self.navigationItem setLeftBarButtonItem:nil animated:YES];
    self.masterPopoverController = nil;
}

- (IBAction)bgroundColor:(id)sender
{
    [[self view] setBackgroundColor:[UIColor blueColor] ];
    [[self view] setBackgroundColor:[UIColor redColor] ];    

}



- (IBAction)dispMessage:(id)sender
{
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Have a nice day"
                                                      message:@"Have a nice day"
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles:nil];

}
@end

Answer 1

It appears that your detailItem property is declared with the type of id. You should do one of the following:

• Declare it with a type that exposes the managedObjectContext property, or
• Add a type cast of self.detailItem to a class exposing the managedObjectContext property, or
• Change the syntax to call managedObjectContext as a method

The last change can be done like this:

NSError *error = nil;
if (![[self.detailItem managedObjectContext] save:&error])

In order for this to work, your .m file needs to include the header for the class that exposes the managedObjectContext property.