iphone - controlling display coordinates of view item added to toolbar

Question

I want to have precise control over the custom view I add to my UINavigationController toolbar. More specifically.. i want to display a UILable ontop of the items in my toolbar.

I have a toolbarItems initially set up with some UIBarButtonItems. The effect I'm trying to achieve is programmatically expand the height of the toolbar, and then display a UILabel ontop of the rest of the buttons.. this is what I currently have:

-(void)expandToolBar:(NSString *)title {

    UIToolbar* toolBar =self.navigationController.toolbar;
    CGRect toolbarFrame = toolBar.frame;

    [UIView animateWithDuration:0.25f delay:0 
                        options:UIViewAnimationOptionLayoutSubviews animations:^{

        // expand toolbar frame vertically
        [toolBar setFrame:
         CGRectMake(toolbarFrame.origin.x,
                    toolbarFrame.origin.y-15,
                    toolbarFrame.size.width,
                    toolbarFrame.size.height + 15)];

    } completion:^(BOOL finished){
        [UIView animateWithDuration:0.50f animations:^{
            // some code here to move the existing toolbar items lower
            // ie to make space for the label

            UILabel* label = [[UILabel alloc] initWithFrame:labelFrame];
            [label setBackgroundColor:[UIColor clearColor]];
            label.text = title;

            UIBarButtonItem *labelItem = [[UIBarButtonItem alloc] 
                                                             initWithCustomView:label];

            // add label to toolbar
            NSMutableArray *newItems = [self.toolbarItems mutableCopy];
            [newItems addObject:labelItem];
            self.toolbarItems = newItems;
        }];
    }];
}

the result of this is that all the existing buttons get squashed, and the label takes their place. The problem is that If I try to get a little too creative and start manually messing with the subviews of the toolbar, I start wandering into undocumented API land, something Apple won't tolerate. Ideas?

Answer 1

What's your actual question? If what you're doing is legal or not? I use some similar tricks to get from the UIBarButtonItem to the view that is represented from it, and it has never been a problem.

For example, I use following snippet without any issues. Technically this isn't using private API per so, but relying on undocumented view structure and here also part of the class names, so you really should know what you're doing. Please also file a radar that UIBarButtonItem is messed up and misses an obvious flag to get to the actual view.

static UIView *PSToolbarViewForBarButtonItem(UIToolbar *toolbar, UIBarButtonItem *barButtonItem) {
    UIView *barButtonView = nil;
    for (UIControl *subview in toolbar.subviews) {
        if ([NSStringFromClass([subview class]) hasPrefix:@"UIToolbarB"] && [subview isKindOfClass:[UIControl class]]) {
            for (UIBarButtonItem *aBarButtonItem in [subview allTargets]) {
                if (barButtonItem == aBarButtonItem) { barButtonView = subview; break; }
            }
        }
    }
    return barButtonView;
}

Also, if you go that route, write code that will fail gracefully if for any reason the view for the toolbar can't be found. I know some apps that go my route, while lots of others don't even bother and simply write their own code to create a toolbar.