ImageOptim plugin for the Sketch app
ImageOptim.sketchpluginto install the plugin.
The Plugin uses two methods for asset compression:
Automatically, whenever you export an asset from Sketch using the File › Export… menu option or the Export button in the toolbar.
When you choose the Plugins › ImageOptim › Export and Optimize All Assets… menu option. You'll be asked for a path where your assets will be exported, and then the plugin will export every exportable layer from your document, and run the assets through ImageOptim.
Please note that both methods won't block Sketch's UI when running, so you'll be able to keep on working while the compressors run. Compression will be done in a separate ImageOptim app. You can switch to the ImageOptim app to see progress and compression results.
Thanks to Ale Muñoz for creating ImageOptim-inspired plugin, which this plugin is based on. We've come a full circle :)