pushViewController in Xcode

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]));
    }
}

You'll need to give us more detail on what your problem is. What's happening? Are you getting an error? — glenstorey
– glenstorey, Commented May 25, 2012 at 2:55
It just doesn't be able to go to another view when I clicked on the table cells. — user486174
– user486174, Commented May 25, 2012 at 3:05

Krishnabhadra · Accepted Answer · 2012-05-25 03:20:08Z

3

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:
}

edited May 25, 2012 at 3:20

Krishnabhadra

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answered May 25, 2012 at 3:08

CodaFi

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1 Comment

CodaFi Over a year ago

I would be much obliged if someone could format this for me, seeing as I typed this out on an iPhone.

Carter Cai · Accepted Answer · 2012-05-25 03:17:09Z

0

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.

answered May 25, 2012 at 3:17

Carter Cai

112 bronze badges

1 Comment

Paresh Navadiya Over a year ago

why do u mean by not use self.navigationController?

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