Gap when changed of viewcontroller - ios

Question

I'm implementing an application, in which i use several view controllers. But i've found a strange behaviour of my app' when it changes of viewcontroller. Let me explain :
We are in a first viewcontroller, his init method is :
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
Menu = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];
self.view.backgroundColor = [UIColor greenColor];
[self.view addSubview:Menu];
[Menu release];
}
return self;
}
After that, to change of viewcontroller and pass from the first to another, i call this method :
-(void)GoPlay
{
if (!parametresviewcontroller)
{
parametresviewcontroller = [[ParametresViewController alloc]init];
}
UIView *menuView = menuviewcontroller.view;
UIView *paramView = parametresviewcontroller.view;
[menuviewcontroller viewWillAppear:NO];
[parametresviewcontroller viewWillDisappear:NO];
[menuView removeFromSuperview];
[self.view addSubview:paramView];
[menuviewcontroller viewDidAppear:NO];
[parametresviewcontroller viewDidDisappear:NO];
}
So the init method of the second viewcontroller is called, i put it next :
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
Parametres = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];
Parametres.backgroundColor = [UIColor redColor];
[self.view addSubview:Parametres];
[Parametres release];
}
return self;
}
And the result is :
Why this strange behavior occured ? I really don't understand why the is a gap between the first and the second one...
Thank you ! =)

Answer 1

Ok, The problem is, both the class Is a UIViewController and you have set statusbar for both ViewController's View in XIB file. When you set StatusBar Than the view frame changes its y to 20 pixel below means you have set it to 0 but originally it is 20.
So when you add subView second ViewController's view on the first ViewController's View before doing this set:
secondViewController.view.frame = firstViewController.view.bounds;
. This will solve your problem.

Answer 2

First of all, DO NOT CALL viewWillAppear, viewWillDisappear, viewDidAppear and viewDidDisappear by yourself, this methods are called by the OS in some specific points of a UIViewController life-cycle.
Second, initWithNibName is not the proper method for adding subviews to the controller's view, for that you should use viewWillAppear, viewDidAppear or viewDidLoad.
Third, what you are doing is not changing of view controllers is simply adding a view controller's view to another view controller view, for changing UIViewController you should use addChildViewController: and removeFromParentViewController methods or use UINavigationController

Answer 3

I've found a solution : iPhone hiding StatusBar shifts view down by 20 pix
Use
[self setWantsFullScreenLayout:YES];
in the init method in my case.
Thank you all !