Question

I’d like to use a popover view for iPhone.
I found a 3rd party library and author says some of its method is utilizing a private method.(which will cause problem when submitting to app store)
But I don’t see where is private method being used in his code.
Can you spot them?

[barButtonItem performSelector:@selector(view)] is considered to be calling a private method?

https://github.com/sonsongithub/PopupView/blob/master/SNPopupView%2BUsingPrivateMethod.m

- (void)showFromBarButtonItem:(UIBarButtonItem*)barButtonItem inView:(UIView*)inView animated:(BOOL)animated {

        if(![barButtonItem respondsToSelector:@selector(view)]) {
            // error
            return;
        }

    UIView *targetView = (UIView *)[barButtonItem performSelector:@selector(view)];
    UIView *targetSuperview = [targetView superview];

    BOOL isOnNavigationBar = YES;

    if ([targetSuperview isKindOfClass:[UINavigationBar class]]) {
        isOnNavigationBar = YES;
    }
    else if ([targetSuperview isKindOfClass:[UIToolbar class]]) {
        isOnNavigationBar = NO;
    }
    else {
        // error
        return;
    }

    CGRect rect = [targetSuperview convertRect:targetView.frame toView:inView];

    CGPoint p;
    p.x = rect.origin.x + (int)rect.size.width/2;

    if (isOnNavigationBar)
        p.y = rect.origin.y + rect.size.height + BAR_BUTTON_ITEM_UPPER_MARGIN;
    else
        p.y = rect.origin.y - BAR_BUTTON_ITEM_BOTTOM_MARGIN;

    [self showAtPoint:p inView:inView animated:animated];
}

Answer 1

You’re not supposed to access the view property of a UIBarButtonItem. That’s where the private call is:

if(![barButtonItem respondsToSelector:@selector(view)]) {
    // error
    return;
}

UIView *targetView = (UIView *)[barButtonItem performSelector:@selector(view)];

See the official doc for UIBarButtonItem, it has no public view property.

Though, it’s not really a private call as the view method is perfectly legal and will not trigger some alert (like if you used a method name that’s only used by private calls), so Apple shouldn’t notice it. But I only said shouldn’t, not won’t.