AssetSizer for Mac – AssetSizer lets you generate .imageset assets for your Xcode projects in seconds! Select an image file, change output parameters if necessary, and export the assets. AssetSizer takes large images and cleanly scales them down into many sizes. Additionally, you can generate the AppIcon.imageset for both iOS and Mac apps. This app used to be for sale for $1.99 on the Mac App Store but is no longer available on there due to me maintaining too many things. It is now available for free from here.
Minimum System Requirements: macOS 10.10
Download AssetSizer.zip (500kb) (Compiled Feb 12, 2023)
This used to be on the Mac App Store, but I have too many projects to maintain, so I am distributing this without the sandbox or review layer.