Why the background image of UIButton in iOS does not display correctly

Mainly in the introduction of the image into the project, there is no choice destination:copy items if needed.　　

No choice destination:copy items if needed , an image can only exist in the project as a link, and when the image moves the path, the image in the project will not display properly.

So, in the future as long as the other resources into the project, you have to tick this item, the resources will be copied a copy into the project, rather than in the form of a link in the project.

Why the background image of UIButton in iOS does not display correctly