Question

I am new to iPhone programming and trying to grasp the concept of RootViewController.

Scenario:

I have 3 views

1. RootViewController – Parent View
2. SportsViewController – Sub View 1
3. CricketViewController – Sub View 2

Both the subview have to be in FullScreenMode, so tab-bar or navigation bar cannot be used.

At first, Sub View 1 is loaded which is having some content and a DONE button on it.
Once user press DONE button then Sub View 1 has to be unloaded and RootViewController should load the Sub View 2.

Query

I have successfully displayed SubView 1 and when user taps on DONE then I can unload it. But I did n’t get how should I notify the RootViewController from Sub View 1 that Sub View 1 has unloaded and now it should load the Sub View 2?

Thanks in Advance

Paras Mendiratta

Answer 1

Here is my code where I tried to use delegate pattern.

The problem is the sub view 1 (videoPlayer) is not able to call the delegate methods. 🙁

ViewSwitcher.h – Root Controller

@class VideoPlayer; //Sub View 1
@class LandingPage; //Sub View 2

@protocol viewSwitcherDelegate 

-(void)notifyViewSwitcher;

@end

@interface ViewSwitcher : UIViewController 
{
   id <viewSwitcherDelegate> delegate;
}

@property (nonatomic, retain) VideoPlayer *videoPlayer;
@property (nonatomic, retain) LandingPage *landingPage;

@property(assign) id <viewSwitcherDelegate> delegate;

-(void)loadSecondView;
-(void)delegateSetInSubView;

@end

ViewSwitcher.m – Implementation

@synthesize videoPlayer;
@synthesize landingPage;
//@synthesize delegate;

// 1.4 -> Declare the delegate constructor
- (id <viewSwitcherDelegate>)delegate
{
    return delegate;
}

// 1.5 -> Declare the setDelegate method
- (void)setDelegate:(id <viewSwitcherDelegate>)v
{
    delegate = v;
}
- (void)viewDidLoad
{
    VideoPlayer *videoController = [[VideoPlayer alloc] initWithNibName:@"VideoPlayer" bundle:nil];
    self.videoPlayer = videoController;
    [self.view insertSubview:videoController.view atIndex:0];
    [videoController release];
    [super viewDidLoad];
}

-(void)loadSecondView
{
    NSLog(@"Call for loading 2nd View");
}

VideoPlayer.h – SubView 1 (Movie Player)

@interface VideoPlayer : UIViewController <viewSwitcherDelegate>
{
    ViewSwitcher *viewSwitcher;
    MPMoviePlayerController *videoController;
}

@end

VideoPlayer.m – implementation

-(void)notifyViewSwitcher
{
    NSLog(@"notifyViewSwitcher called.");
    //Attempted to call the loadSecondView of ViewSwitcher

I tried calling delegate’s method but in log nothing is printed.

    [viewSwitcher loadSecondView];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    // Setting the delegate
    viewSwitcher.delegate = self;
    return self;
}

- (void)viewDidLoad
{
    NSString *urlStr = [[NSBundle mainBundle] pathForResource:@"bumper.mp4" ofType:nil];
    NSURL *url = [NSURL fileURLWithPath:urlStr];

    videoController = [[MPMoviePlayerController alloc] initWithContentURL:url];
    videoController.controlStyle = MPMovieControlStyleNone;
    [self.view addSubview:videoController.view];

    videoController.view.frame = CGRectMake(0, 0, 480, 320);
    videoController.fullscreen = YES;

    // Remove the status bar from this view.
    [[UIApplication sharedApplication] setStatusBarHidden:YES animated:UIStatusBarAnimationFade];

    // TODO: This observer needs to be removed.
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(playbackStateChange:)
                                                 name:MPMoviePlayerPlaybackDidFinishNotification
                                               object:videoController];

    // Play the video.
    [videoController play];

    [super viewDidLoad];
}

// Receives notification once movie is finished.
-(void)playbackStateChange:(NSNotification*)notification
{
    // TODO: Switch the view.

    NSLog(@"Notification = %@", notification);
    [self notifyViewSwitcher];
}

Here is the LOG:-

2011-08-03 02:44:47.333 My Video Player[24016:207] Notification = NSConcreteNotification 0x5768280 {name = MPMoviePlayerPlaybackDidFinishNotification; object = <MPMoviePlayerController: 0x5740940>; userInfo = {
    MPMoviePlayerPlaybackDidFinishReasonUserInfoKey = 0;
}}
2011-08-03 02:44:47.337 My Video Player[24016:207] notifyViewSwitcher called.