pushViewController in Xcode - objective-c

Question

I'm trying to push a view from a table cell to another view, I know that there's a lot of tutorials out there, I've tried a lot of them, been trying for 2 days and still can't get it working, here's my code..
AppDelegate.h
#import <UIKit/UIKit.h>
#class RootViewController;
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#property (strong, nonatomic) RootViewController *rootViewController;
#end
AppDelegate.m
#import "AppDelegate.h"
#import "RootViewController.h"
#implementation AppDelegate
#synthesize window = _window;
#synthesize rootViewController;
- (void)dealloc
{
[_window release];
[super dealloc];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.rootViewController = [[[RootViewController alloc] initWithNibName:#"RootViewController" bundle:nil] autorelease];
self.window.rootViewController = self.rootViewController;
[self.window makeKeyAndVisible];
return YES;
}
#end
RootViewController.h
#import <UIKit/UIKit.h>
#interface RootViewController : UITableViewController{
NSMutableArray* array;
}
#property(nonatomic, retain)NSMutableArray* array;
#end
RootViewController.m
#import "RootViewController.h"
#import "SubLevelViewController.h"
#implementation RootViewController
#synthesize array;
- (void)viewDidLoad {
[super viewDidLoad];
array = [[NSMutableArray alloc] init];
[array addObject:#"One"];
[array addObject:#"Two"];
[array addObject:#"Three"];
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
self.navigationItem.rightBarButtonItem = self.editButtonItem;
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
// Release anything that can be recreated in viewDidLoad or on demand.
// e.g. self.myOutlet = nil;
}
#pragma mark Table view methods
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [array count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
NSString *cellValue = [array objectAtIndex:indexPath.row];
cell.textLabel.text = cellValue;
// Configure the cell.
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
SubLevelViewController *sub = [[SubLevelViewController alloc] initWithNibName:#"SubLevelViewController" bundle:nil];
sub.title = #"My First View";
[self.navigationController pushViewController:sub animated:YES];
}
- (void)dealloc {
[array release];
[super dealloc];
}
#end
and main.m
#import <UIKit/UIKit.h>
#import "AppDelegate.h"
int main(int argc, char *argv[])
{
#autoreleasepool {
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}

Answer 1

Actually, your problem is simple, you reference self.navigationController, yet the view controller has no navigation controller set up in the AppDelegate! You're sending a message to nil, which produces nil (ergo, nothing happens). Try this in the appDelegate:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.rootViewController = [[[RootViewController alloc] initWithNibName:#"RootViewController" bundle:nil] autorelease];
UINavigationController * controller = [[[UINavigationController alloc]initWithRootViewController:self.rootViewController]autorelease];
    self.window.rootViewController = controller;
    [self.window makeKeyAndVisible];
return YES:
}

Answer 2

Agree with CodaFi, you need to create a UINavigationController and remember it to push and pop any UIViewController if you want to keep the push/pop stack. Do not use self.navigationController.