When you open 4D v18 Developer Edition on High Sierra, the following warning message is displayed:

4D can't be opened because it is from an unidentified developer.

This message applies only to the 4D Developer Edition; you have NO issues with the 4D Server or merged application.

We recommend you to use Mojave or Catalina macOS.

If you prefer to use on High Sierra macOS for development, there are two possible workarounds:

• You install SWIFT, so the 4D application will be identified.
• Or you can go to the "system preferences > security” dialog, and click on the "Open anyway" button (Be aware, this is to be done after each download of a new build).

Note about SWIFT 5:

Starting with Xcode 10.2, Swift 5 command line programs you build require the Swift 5 runtime support libraries built into macOS. These libraries are included in the OS starting with macOS Mojave 10.14.4. When running on earlier versions of macOS, this package must be installed to provide the necessary Swift 5 libraries. This package is not necessary for apps with graphical user interfaces.