I want to add a pop up when someone pushes the "Back" button of my iOS App, to ask the user if he really wants to come back. Then, depending on the user's response, I would like to undo the action or proceed. I've tried to add the code in the viewWillDisappear function of my view and then write the proper delegate but it doesn't work, because it always change the view and then show the pop up. My code is:
-(void) viewWillDisappear:(BOOL)animated {
_animated = animated;
if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) {
UIAlertView *alert_undo = [[UIAlertView alloc] initWithTitle:@"UIAlertView"
message:@"You could be loosing information with this action. Do you want to proceed?"
delegate:self
cancelButtonTitle:@"Go back"
otherButtonTitles:@"Yes", nil];
[alert_undo show];
}
else [super viewWillDisappear:animated];
}
And the delegate implementation is:
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
NSString *title = [alertView buttonTitleAtIndex:buttonIndex];
if([title isEqualToString:@"Yes"])
{
[super viewWillDisappear:_animated];
}
}
This is not working at all. Does anybody now a better way to do it or what could be wrong?
Thank you very much,
Once -viewWillDisappear:
is called, there's no stopping your viewController
from disappearing.
You should ideally, override the navigationBar
's back button and in it's method, display the alert (the rest being pretty much the same)
- (void)viewDidLoad
{
//...
UIBarButtonItem *bbtnBack = [[UIBarButtonItem alloc] initWithTitle:@"Back"
style:UIBarButtonItemStyleBordered
target:self
action:@selector(goBack:)];
[self.navigationItem setBackBarButtonItem: bbtnBack];
}
- (void)goBack:(UIBarButtonItem *)sender
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert"
message:@"...Do you want to proceed?"
delegate:self
cancelButtonTitle:@"No"
otherButtonTitles:@"Yes", nil];
[alert show];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
switch(buttonIndex) {
case 0: //"No" pressed
//do something?
break;
case 1: //"Yes" pressed
//here you pop the viewController
[self.navigationController popViewControllerAnimated:YES];
break;
}
}
NOTE: Don't forget to declare <UIAlertViewDelegate>
in the .h file of this viewController