Removing and reinserting UIView into UIViewController

Question

I have a UIViewController that contains a UIView. Between every time the viewcontroller is displyaed, the UIView has to be cleared and the content reloaded. The problem is that the old content still appears in the UIView.

Load data before controller becomes visible:

- (void)viewWillAppear:(BOOL)animated
{
    contentView = [[ContentView alloc] initWithFrame:CGRectMake(10, 10, 100, 100)];
    contentView.userInteractionEnabled = NO;
    [self.view addSubview:contentView];

    if([self loadContentData] == NO) {
        [contentView release];
        return NO;
    }
    return YES;
}

Remove content after controller is hidden:

- (void)viewDidDisappear:(BOOL)animated
{
    [contentView removeFromSuperview];
    [contentView release];
}

Why is this cleanup not sufficient?

Answer 1

Try:

- (void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
    [contentView removeFromSuperView];  //releases contentView
}

You must call super's method when overriding this method.

Additionally, contentView appears to be over-released in the code you've posted which makes me believe you are retaining it possibly somewhere in your real code. If this is the case, you may have over-retained contentView, which will prevent it from being released and cleaned up from your view hierarchy.

I would suggest you explore something along these lines:

- (void)viewWillAppear:(BOOL)animated
{
    contentView = [[[ContentView alloc] initWithFrame:CGRectMake(10, 10, 100, 100)] autorelease];
    contentView.userInteractionEnabled = NO;
    [self.view addSubview:contentView];

    if([self loadContentData] == NO) {
        //[contentView release];  //ContentView is now autoreleased and will be dropped when the method exits.
        return NO; //this probably has a compiler warning, since it is a (void) method
    }
    return YES; //this probably has a compiler warning, since it is a (void) method
}