Question

IBAction does nothing. Logs “Back” to console so the connection’s OK. self.topView also does nothing when the IBAction is called

-(IBAction)loadSettingsView:(id)sender;

{

    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        [[NSBundle mainBundle] loadNibNamed:@"settingsView_iphone" owner:self options:nil]; 
    } else {
        [[NSBundle mainBundle] loadNibNamed:@"settingsView_ipad" owner:self options:nil];
    }
    [self.view addSubview:topView];
}

-(IBAction)loadMainView:(id)sender;
{
    [topView removeFromSuperview];
    NSLog(@"back");

}

Answer 1

I hope I am not making too many assumptions here, but this should solve your problem. I am assuming topView is a member of the current class:

-(IBAction)loadSettingsView:(id)sender;

{

    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        topView = [[[NSBundle mainBundle] loadNibNamed:@"settingsView_iphone" owner:self options:nil] objectAtIndex:0]; 
    } else {
        topView = [[[NSBundle mainBundle] loadNibNamed:@"settingsView_ipad" owner:self options:nil] objectAtIndex:0];
    }
    [self.view addSubview:topView];
}

-(IBAction)loadMainView:(id)sender;
{
    [topView removeFromSuperview];
    NSLog(@"back");

}

Basically, the loadNibNamed method you are using is returning an array with all the top-level views in the nib. If you want a reference to these views (And here I am assuming there is one view in the nib), you need to actually assign your topView variable. Currently topView is probably nil, so your removeFromSuperview call is doing nothing.