iOS iPhone app crashing

@implementation UserNameViewController

@synthesize detailItem;
@synthesize tableView;

- (id)init
{
	if (self = [super init]) {
		self.title = @"Accounts";

	}
	return self;
}

- (void)loadView
{
    tableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame] style:UITableViewStylePlain];
	tableView.delegate = self;
	tableView.dataSource = self;	
	tableView.separatorStyle = UITableViewCellSeparatorStyleSingleLine;
	
	self.view = tableView;
}

- (void)dealloc
{
	tableView.dataSource = nil;
	tableView.delegate = nil;
	[passwordViewController release];
	[tableView release];
	[super dealloc];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
	return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
	return [[detailItem objectForKey:@"accounts"] count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath withAvailableCell:(UITableViewCell *)availableCell {
	
	UISimpleTableViewCell *cell = nil;
	if (availableCell != nil) {
		cell = (UISimpleTableViewCell *)availableCell;
	} else {
		cell = [[[UISimpleTableViewCell alloc] init] autorelease];
	}

	// Set the value in the cell
	NSArray *usernames = (NSArray *)[detailItem objectForKey:@"accounts"];
	NSDictionary *account = (NSDictionary *)[usernames objectAtIndex:indexPath.row];
	cell.text = [account objectForKey:@"username"];
	return cell;
}

- (void)tableView:(UITableView *)tableView selectionDidChangeToIndexPath:(NSIndexPath *)newIndexPath fromIndexPath:(NSIndexPath *)oldIndexPath {
	if (passwordViewController == nil) {
		passwordViewController = [[PasswordViewController alloc] init];
	}
	// Set the detail controller's inspected item to the currently-selected item
	passwordViewController.detailItem = [[detailItem objectForKey:@"accounts"] objectAtIndex:newIndexPath.row];
	[[self navigationController] pushViewController:passwordViewController animated:YES];
}

@end

#import "MasterViewController.h"
#import "UntitledAppDelegate.h"
#import "UserNameViewController.h"

@implementation MasterViewController

@synthesize appController;
@synthesize tableView;

- (id)init
{
	if (self = [super init]) {
		self.title = @"Categories";
	}
	return self;
}

- (void) inspectAction:(id) sender 
{
}

- (void)loadView {
	 UIButton *inspectButton = [UIButton buttonWithType:UIButtonTypeNavigation];
	[inspectButton setTitle:@"A Button" forStates:UIControlStateNormal];
	[inspectButton addTarget:self action:@selector(inspectAction:) forControlEvents:UIControlEventTouchUpInside];
	self.navigationItem.customRightView = inspectButton;
	[inspectButton release];

    tableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame] style:UITableViewStylePlain];
	tableView.delegate = self;
	tableView.dataSource = self;
	tableView.separatorStyle = UITableViewCellSeparatorStyleSingleLine;
	self.view = tableView;
}


- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
	return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (void)didReceiveMemoryWarning
{
	[super didReceiveMemoryWarning]; 
}

- (void)dealloc
{
		
	tableView.dataSource = nil;
	tableView.delegate = nil;
	[tableView release];
	[userNameViewController release];
	[super dealloc];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
	return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
	return [appController.masterList count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath withAvailableCell:(UITableViewCell *)availableCell
{	
	UISimpleTableViewCell *cell = nil;
	if (availableCell != nil) {
		// Use the existing cell if it's there
		cell = (UISimpleTableViewCell *)availableCell;
	} else {
		cell = [[[UISimpleTableViewCell alloc] initWithFrame:CGRectZero] autorelease];
		cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
	}
	
	// Get the object to display and set the value in the cell
	NSDictionary *itemAtIndex = (NSDictionary *)[appController.masterList objectAtIndex:indexPath.row];
	cell.text = [itemAtIndex objectForKey:@"title"];
	return cell;
}


- (void)tableView:(UITableView *)tableView selectionDidChangeToIndexPath:(NSIndexPath *)newIndexPath fromIndexPath:(NSIndexPath *)oldIndexPath {

	// Create the detail view lazily
	if (userNameViewController == nil) {
		userNameViewController = [[UserNameViewController alloc] init];
	}
	// Set the detail controller's inspected item to the currently-selected item
	userNameViewController.detailItem = [appController.masterList objectAtIndex:newIndexPath.row];
	[[self navigationController] pushViewController:userNameViewController animated:YES];
}
@end