Defold technical artist Martin Dahlin just released the Photoshop extension they use in house at King for exporting GUI designs from Adobe Photoshop to the Defold game engine. The extension enables you to export such information as layer name, size and position, with additional data such as pivot position and slice9 properties stored on a per layer basis. The results are ultimately exported in Defold’s .gui format.
You can learn more about the extension here.