Before Xcode9
In Xcode9 and earlier versions, after opening the storyboard, Object libraryit will appear at the bottom of the inspectors.
After Xcode9
Starting from Xcode 10, Object Libraryit is not displayed by default and needs to be opened manually.
Open Object Library
In the Interface Builder interface, click the solution +number in the upper right to pop up Object Library.
Unlike before, in the new version of Xcode, the component library is displayed in the form of a floating window, which can be dragged at will.
The usage is the same as before, just click and hold the desired component and drag it to the storyboard.
