UITextField shouldBeginEditing called every other time?

Question

iOS unfortunately doesn't have a dropdown picker like html does with the tag. I decided that I was finally going to create one for my app, and it looks and works great. My dropdown object is a subclass of UITextField. However, I changed something and now it only works some of the time.

User interaction is enabled, but I don't want the textfield to be editable. The class in which my dropdown subclass resides is UITextField delegate, and should receive delegate methods for UITextField.

I have - (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{ where I check to see if the textfield in question is a dropdown menu, and if it is, I call a method to instantiate a popover and disable editing, but the dropdown only appears on every other tap.

For example, i'll tap the "textfield" and my popover displays. I tap out so the popover goes away, then I tap on the "textfield" and nothing happens. I tap on the textfield once again and the popover appears. No idea why this is happening, here is what i'm doing:

.h

subclass : UIViewController<UITextFieldDelegate>

.m

dropdownTextField.delegate = self;
...
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    if(textField == self.measurementSelect){
        NSLog(@"IM CALLED");
        [self showPopover:textField];
        return NO;
    }
    return YES;
}

-(void)showPopover:(id)sender{
    if (_measurementPicker == nil) {
        _measurementPicker = [[iPadMeasurementSelect alloc] initWithStyle:UITableViewStylePlain];
        _measurementPicker.delegate = self;
    }

    if (_measurementPopover == nil) {
        _measurementPopover = [[UIPopoverController alloc] initWithContentViewController:_measurementPicker];
        [_measurementPopover presentPopoverFromRect:self.measurementSelect.frame inView:self.conversionView permittedArrowDirections:UIPopoverArrowDirectionLeft animated:YES];

    }
    else {
        [_measurementPopover dismissPopoverAnimated:YES];
        _measurementPopover = nil;
    }
}

Every tap gets nslogged, so I assume my popover method is the culprit of this problem. Any ideas?

Answer 1

Let's rewrite by teasing apart existence of the UI elements and the visible state of the popover:

// canonical lazy getters for UI elements

- (iPadMeasurementSelect *)measurementPicker {
    if (!_measurementPicker) {
        _measurementPicker = [[iPadMeasurementSelect alloc] initWithStyle:UITableViewStylePlain];
        _measurementPicker.delegate = self;
    }
    return _measurementPicker;
}

- (UIPopoverController *)measurementPopover {
    if (!_measurementPopover) {
        _measurementPopover = [[UIPopoverController alloc] initWithContentViewController:self.measurementPicker];
    }
    return _measurementPopover;
}

// now the show/hide method makes sense.  it can take a bool about whether to show or hide
-(void)showPopover:(BOOL)show {

    if (show) {
        [self.measurementPopover presentPopoverFromRect:self.measurementSelect.frame inView:self.conversionView permittedArrowDirections:UIPopoverArrowDirectionLeft animated:YES];
    } else {
        [self.measurementPopover dismissPopoverAnimated:NO];
        // if you want/need to create a new one each time it is shown, nil the popover here, like this:
        // self.measurementPopover = nil;
    }
}

When the textField begins editing, show the popover like this:

[self showPopover:YES];

And when the delegate gets the didEndEditing message:

[self showPopover:NO];