Level1ViewController.m

/*
     File: Level1ViewController.m
 Abstract: The application's level 1 view controller.
  Version: 1.3
 
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#import "AppDelegate.h"
#import "Level1ViewController.h"
#import "Level2ViewController.h"
 
@implementation Level1ViewController
 
@synthesize listContent, level2ViewController, myTableView;
 
- (void)dealloc
{
    [myTableView release];
    [listContent release];
    [level2ViewController release];
    [super dealloc];
}
 
- (void)awakeFromNib
{   
    self.title = @"Level 1";
}
 
 
#pragma mark UIViewController delegates
 
- (void)viewWillAppear:(BOOL)animated
{
    [myTableView reloadData];   // populate our table's data
    
    NSIndexPath *tableSelection = [myTableView indexPathForSelectedRow];
    [myTableView deselectRowAtIndexPath:tableSelection animated:NO];
}
 
 
#pragma mark UITableView delegates
 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}
 
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [listContent count];
}
 
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // save off this level's selection to our AppDelegate
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDelegate.savedLocation replaceObjectAtIndex:0 withObject:[NSNumber numberWithInteger:indexPath.row]];
    [appDelegate.savedLocation replaceObjectAtIndex:1 withObject:[NSNumber numberWithInteger:-1]];
    [appDelegate.savedLocation replaceObjectAtIndex:2 withObject:[NSNumber numberWithInteger:-1]];
    
    // provide the 2nd level its content
    level2ViewController.listContent = [[listContent objectAtIndex:indexPath.row] objectForKey:kChildrenKey];
    
    // move to the 2nd level
    [[self navigationController] pushViewController:level2ViewController animated:YES];
    
    // commit the drill down location preference setting
    [[NSUserDefaults standardUserDefaults] setObject:appDelegate.savedLocation forKey:kRestoreLocationKey];
}
 
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kCellIdentifier];
    if (cell == nil)
    {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kCellIdentifier] autorelease];
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    }
    
    // get the view controller's info dictionary based on the indexPath's row
    NSDictionary* item = [listContent objectAtIndex:indexPath.row];
    cell.textLabel.text = [item objectForKey:kItemTitleKey];
    
    return cell;
}
 
// User was last at level 2 or deeper
//
// note: this is a part of a chain reaction down each level (2nd, 3rd, etc.)
// so that each level restores itself and pushes further down until there's no further stored selections.
//
- (void)restoreLevel:(NSArray*)items withSelectionArray:(NSArray *)selectionArray
{
    // user was last at level 2 or deeper
    //
    self.listContent = items;   // remember our content here at level 1 in case user navigates back to this level
    
    // move in level 2 and restore its content (not animated since the user should not see the restore process)
    [[self navigationController] pushViewController:level2ViewController animated:NO];
    
    // get the level 2 content
    NSInteger itemIdx = [[selectionArray objectAtIndex:0] integerValue];
    NSArray *itemContent = [[items objectAtIndex:itemIdx] objectForKey:kChildrenKey];
    
    // narrow down the selection array for level 2
    NSArray *newSelectionArray = [selectionArray subarrayWithRange:NSMakeRange(1, [selectionArray count]-1)];
    
    // restore that level
    [level2ViewController restoreLevel:itemContent withSelectionArray:newSelectionArray];
}
 
- (void)viewDidAppear:(BOOL)animated
{
    // we have moved to level 1, remove it's stored selection
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDelegate.savedLocation replaceObjectAtIndex:0 withObject:[NSNumber numberWithInteger:-1]];
    
    // commit the drill down location preference setting
    [[NSUserDefaults standardUserDefaults] setObject:appDelegate.savedLocation forKey:kRestoreLocationKey];
}
 
@end