On Apple Silicon (arm64)

If you need the GUI (recommended), then you must first install a working distribution of tcl-tk on your mac, as the version coming with Macos is broken on these targets. Because we tested it, we recommend to install homebrew (see https://brew.sh/ for instructions), and then to install the homebrew tcl-tk package by:

brew install tcl-tk

IMPORTANT: the tina GUI (nd.app) does not handle the macos dark mode yet; in dark mode it will show wrong colors. Hence make sure you open nd.app in light mode !

Then proceed as explained below for Intel macs.

On Intel macs (amd64)

Step 1. On versions of MacOS with GateKeeper enabled (10.8,9,...), GateKeeper will prevent installing tina and pretend that the application is damaged.
It is not; it is simply that tina is not signed by a registered Apple developper.

On such systems, tina can be installed as follows:

1. remove any installed version of tina

2. disable GateKeeper in System Preferences

On 10.10 for instance, this is done by:
System Preferences > Security & Privacy > General > Allow apps downloaded from: > Anywhere
From 10.12 (Sierra), you need first to make "Anywhere" appear again by typing the following line in a terminal (Thanks Jean-Luc):
sudo spctl --master-disable

3. download a suitable version of tina

4. install and launch nd: open the dmg archive downloaded, slide nd.app to /Applications, then open it

5. re-enable GateKeeper if desired

From 10.12 (Sierra), you may wish to revert the security options as they were before by typing the following line in a terminal:
sudo spctl --master-enable

Step 2. On versions of MacOS with XProtect enabled (notably Monterey and later versions), and depending which tool was used to download tina, XProtect may flag nd.app as unsafe and prevent to launch it.

If nd.app fails to work after step 1 above, it may be that is was considered unsafe by XProtect and its quarantine bit set. This can be fixed by clearing the extended attributes of nd.app as follows (in a terminal): navigate to the folder including nd.app, then type:

sudo xattr -rc nd.app

Alternatively, remove nd.app and the downloaded tina dmg and download it again using curl or wget instead of your usual browser. curl or wget will not invoke XProtect.

For more information, check e.g.

App is damaged and cannot be opened

GateKeeper

XProtect

allow-applications-downloaded-from-anywhere-in-macos-sierra

Safely open apps on your Mac (scroll down for more Mojave and Catalina options)

open-a-mac-app-from-an-unidentified-developer (12.0)