Apple has changed the way to find and add UI views and controls to storyboard in XCode 10. In Xcode 9 and older versions, the UI views and controls are available in Inspector area at the right bottom corner.
In XCode 10, A new button (called "library") was added in top right corner, clicking this button shows the regular ui element selecting window, from there, developers can select a UI control, and then drag and drop it to the storyboard's view controller. After adding the control to the view controller, the library window will close by itself automatically.
Sometimes, you may need to add multiple UI element into the storyboard, in that case, to avoid repeatedly click the toolbar button to open the library window, you can hold the option key when click the library toolbar button.
In XCode 10, A new button (called "library") was added in top right corner, clicking this button shows the regular ui element selecting window, from there, developers can select a UI control, and then drag and drop it to the storyboard's view controller. After adding the control to the view controller, the library window will close by itself automatically.
Sometimes, you may need to add multiple UI element into the storyboard, in that case, to avoid repeatedly click the toolbar button to open the library window, you can hold the option key when click the library toolbar button.
