modalPresentationStyle from button click - ios

Question

I have a _exampleButton:
_exampleButton = [UIButton buttonWithType:UIButtonTypeCustom];
[_exampleButton setBackgroundColor:[UIColor redColor]];
[_exampleButton addTarget:self action:#selector(certificatesButtonTouched) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:_exampleButton];
and the action:
-(void)certificatesButtonTouched
{
if(!_certificatesWindow)
{
_certificatesWindow = [[AWCertificatesViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc]
initWithRootViewController:_certificatesWindow];
navController.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentViewController:navController animated:YES completion:nil];
[_certificatesWindow release];
}
else {
[_certificatesWindow.view removeFromSuperview];
[_certificatesWindow release];
_certificatesWindow = nil;
}
}
this presents the window in modal view controller from other class:
- (void)viewDidLoad
{
[super viewDidLoad];
UIBarButtonItem *cancelItem = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
target:self
action:#selector(cancel:)];
self.navigationItem.leftBarButtonItem = cancelItem;
UITableView *table = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame] style:UITableViewStylePlain];
[self.view addSubview:table];
_tableFromButton = table;
}
- (void)cancel:(id)sender
{
[self.presentingViewController dismissViewControllerAnimated:YES
completion:nil];
}
but after clicking the Cancel button, the Modal view controller view disappears, but if I click the _exampleButton again once- it will not appear, so I have to click it twice to show the modal view controller again. What is the problem?

Answer 1

It does this because that is what your code tell it to do...
You dismiss the view controller in -(void)cancel:(id)sender but this will not result in the _certificatesWindow iVar becoming nil in your first view controller. So when you touch the exampleButton again it will execute the else clause and clean up the _certificatesWindow view controller.
You should either use delegation or a code block to have the first view controller dismiss the second or remove the if/else test from your certificatesButtonTouched. Another alternative is to modify this method so that if _certificatesWindow is not nil it is reused -
-(void)certificatesButtonTouched
{
if(!_certificatesWindow)
{
_certificatesWindow = [[AWCertificatesViewController alloc] init];
}
UINavigationController *navController = [[UINavigationController alloc]
initWithRootViewController:_certificatesWindow];
navController.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentViewController:navController animated:YES completion:nil];
}
But this may or may not be desirable depending on what the second view controller shows.
I would also suggest you look at converting to ARC if possible

Answer 2

The problem is after you tap "Cancel", _certificatesWindow still exists when you tap on certificatesButtonTouched. It will go to the Else statement on the First tap to make _certificatesWindow = nil.
if _certificatesWindow is not needed when you tap cancel, you might want to do the following:-
- (void)cancel:(id)sender
{
[self.presentingViewController dismissViewControllerAnimated:YES
completion:nil];
[_certificatesWindow.view removeFromSuperview];
[_certificatesWindow release];
_certificatesWindow = nil;
}

Answer 3

allocate view like this in view did load method
if(!_certificatesWindow)
{
_certificatesWindow = [[ViewController1 alloc] init];
}
-(void)certificatesButtonTouched
{
UINavigationController *navController = [[UINavigationController alloc]
initWithRootViewController:_certificatesWindow];
navController.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentViewController:navController animated:YES completion:nil];
}

Answer 4

replace your code with this
-(void)certificatesButtonTouched
{
if(!_certificatesWindow)
{
_certificatesWindow = [[AWCertificatesViewController alloc] init];
}
UINavigationController *navController = [[UINavigationController alloc]
initWithRootViewController:_certificatesWindow];
navController.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentViewController:navController animated:YES completion:nil];
[_certificatesWindow release];
}