Question

I am attempting to perform a Storyboard segue from a UIbutton that is a day on a calendar to a DayViewController with info on that day. The currentTitle of the sender UIbutton should be passed to a UILabel in the dayView of the DayViewController. It successfully segues to the new VC and assigns the button title to a property therein, however the dayView (and the base view) of my DayViewController is not getting initialized (their addresses in the debugger are both 0x0) and I get a blank page. How can I get these views to initialize in this segue? (I thought views linked to a VC were automatically initialized when segued to?)

Here’s the prepareForSegue getting called:

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(UIButton *)sender
{
    if ([segue.identifier isEqualToString:@"ShowDay"]) {
        DayViewController *vc = segue.destinationViewController;
        [vc setCurrentDayNumber:sender.currentTitle];
}

Here is setCurrentDayNumber in the new VC

-(void)setCurrentDayNumber:(NSString *)currentDayNumber
{
    _currentDayNumber = currentDayNumber;
   [self.dayView setNeedsDisplay];
}    

Here is my view that is linked to DayViewController in the storyboard.

@property (nonatomic, weak) IBOutlet DayView *dayView;

Thanks in advance!

Answer 1

When you declare a property as weak, it will not “hold on” to the value unless someone else has a reference to it as well. When the new view controller is pushed, the old button goes away, leaving currentDayNumber as the only reference, so it automatically sets itself to nil. (This is what weak is supposed to do.)

If you want to keep a reference to it no matter what, use strong instead of weak and make sure to set _currentDayNumber to nil somewhere (like viewDidUnload) so that you don’t retain it forever.