How to use UISegmentControl to change detailViewController of CoreData

I have implemented a UISegmentControl as the rightBarButton of my detailViewCo开发者_如何学Pythonntroller. This view controller displays that of the information passed through from a UITableView. This UITableView's cells are populated with CoreData attribute values.

What I want to do is enable the user to go up and down in the list via the detailViewController. Instead of having to make the user have to go back to the rootViewController, they'll gain the ability to scroll through via the UISegmentControl.

I currently have this in my detailViewController.m

 - (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
 // Setting up UISegmentedControl

// Segmented Control - Custom right bar button with a view
UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:
                                        [NSArray arrayWithObjects:
                                         [UIImage imageNamed:@"arrowdown.png"],
                                         [UIImage imageNamed:@"arrowup.png"],
                                         nil]];

[segmentedControl addTarget:self action:@selector(segmentAction:) forControlEvents:UIControlEventValueChanged];

segmentedControl.frame = CGRectMake(0, 0, 75, 30);
segmentedControl.segmentedControlStyle = UISegmentedControlStyleBar;
segmentedControl.momentary = YES;

UIBarButtonItem *segmentBarItem = [[UIBarButtonItem alloc] initWithCustomView:segmentedControl];
[segmentedControl release];

self.navigationItem.rightBarButtonItem = segmentBarItem;
[segmentBarItem release];
  }

This is then attached to the following method, for detecting the tapped control.

 - (void)segmentAction:(id)sender
 {
UISegmentedControl* segCtl = sender;
// the segmented control was clicked, handle it here 

if([segCtl selectedSegmentIndex]==0){
    NSLog(@"You clicked the down arrow - the segment clicked was %d", [segCtl selectedSegmentIndex]);
}else {

    NSLog(@"You clicked the up arrow - the segment clicked was %d", [segCtl selectedSegmentIndex]);

}



}

I am also curious as to whether or not anyone knows how to detect whether or not there is anymore to go to. So say, if the note loaded is in the first position, then the down arrow is disabled, and if the note loaded is in the last position, the up arrow is disabled. Is this even possible?

Any help would be greatly appreciated.

I'd suggest you to create a formal protocol MyDataSource which provides methods for accessing the data. As a minimum, there must be a method to get number of data objects and object for a specified index.

In your DetailViewController you should have a reference to an object which conforms to MyDataSource. I'd recommend you to use instance of RootViewController as a data source for DetailViewController.

You should also keep track of index of the object that is currently displayed in DetailViewController and update UI appropriately.