DSD+ (Digital Speech Decoder+) is a popular Windows tool that can be used together with an RTL-SDR to decode digital speech signals such as P25 and DMR. There is unfortunately no version for OSX.
However, recently on YouTube user Matthew Miller has uploaded a video showing DSD+ running with CubicSDR on OSX. To do this he used a utility called “Wine Skin” which creates a wrapper that allows Windows software to run on a MAC computer running OSX. This means that DSD+ can be run on directly OSX without the need to use a virtual machine with Windows installed on it.