UIAlert and push segues - ios

Question

I have an IF statement that checks labels to see if a label is empty, if it is show an alert.
if ([_DOBDate.text length] == 0)
{
UIAlertView *message = [[UIAlertView alloc] initWithTitle:#"Cannot Proceed"
message:#"Please Submit your DOB and Gender"
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[message show];
}
later on in the function I have perform segue, like this :
[self performSegueWithIdentifier:#"SetUptoMain" sender:self];
True, the alert does fire when the label is blank, but it also performs the segue. This perform segue line is not in the IF statement. So I would have thought it would have ran the IF statement and stayed there till I pressed OK. OK would be staying on the same view controller.
The segue is performed, is this due to Blocks ? any advice ?
So if the USER pressed Ok from the UIAlert the VC does not move, it stays where it was so the user can enter the details required.
This is my code :
- (IBAction)SettingsSave:(id)sender {
if ([_DOBDate.text length] == 0)
{
UIAlertView *message = [[UIAlertView alloc] initWithTitle:#"Cannot Proceed"
message:#"Please Submit your DOB and Gender"
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[message show];
}
more code...
then at the end
[self performSegueWithIdentifier:#"SetUptoMain" sender:self];
}
thanks

Answer 1

Seems to be an if/else logic issue. Read about it.
-(IBAction)yourAction:(id)sender
{
if ([_DOBDate.text length] == 0)
{
//Show your AlertView as you did
}
else
{
//put the rest of your code, including the performSegue
}
}

Answer 2

UIAlertView doesn't block execution. It runs asynchronously. Therefore the code path will go into your if statement, then continue past it.
If you only want the segue to be performed after the user presses the alert view button then you need to implement UIAlertViewDelegate.
In your header file add something like this:
#interface MyController : UIViewController <UIAlertViewDelegate>
When you create the alert view do it like this:
UIAlertView *message = [[UIAlertView alloc] initWithTitle: #"Cannot Proceed"
message: #"Please Submit your DOB and Gender"
delegate: self
cancelButtonTitle: #"OK"
otherButtonTitles: nil];
[message show];
And add this method to implement the UIAlertViewDelegate.
- (void) alertView: (UIAlertView *) alertView clickedButtonAtIndex: (NSInteger) buttonIndex {
// perform segue here. You can also check what button was pressed based on the button index.
}