Question

I’m currently learning iOS Programming and I have a (hopefully) simple problem:
I wrote a drawing program that works with a customized class of UIView. That gets initialised upon startup in the main view controller in the viewDidLoad method

Image_DrawDraw *drawing = [[Image_DrawDraw alloc] initWithFrame:self.view.bounds];
[self.view addSubview:drawing];

I now want to change my program into a bit more sophisticated. I made a xib File containing some buttons, status bar and and image view. I still want to be able to draw in this new view, precisely over the image view, but not over the status bar or the buttons. But I have problems in initializing my Image_DrawDraw class it just overrides the whole xib and I’m back to my black screen where I can draw.
Thank you for your help!

Answer 1

When you add a subView to a view hierarchy it becomes the last item in the superview’s views array property. The layering order of views is based on the views array, with the lowermost view the item at [views objectAtIndex:0] and the uppermost view the item at [views lastObject]. By arranging all of your other views on the Xib, and then adding your Image_DrawDraw view in code after the Xib has loaded, you are making it the uppermost view, so obscuring your buttons.

Instead of adding it in code, you could place it directly in the Xib.

Add a custom view to your xib. Position it above your existing xib image view, and below the buttons. Set the custom class of the view to Image_DrawDraw.

Now you won’t need either of these lines of code:

Image_DrawDraw *drawing = [[Image_DrawDraw alloc] initWithFrame:self.view.bounds];
[self.view addSubview:drawing];

To refer to you Image_DrawDraw xib view in code, you should make an IBOutlet property for it in your viewController’s @interface, and connect the Xib view to the IBOutlet by CTRL-dragging a line out in the Xib file.