Plist files are an essential file that all macOS apps have. The contents of each file are different of course but you’d be hard-pressed to find an app that doesn’t come with one. A Plist file used to be really easy to edit on macOS and the stock TextEdit app was enough to do that job. That’s changed now since these files are rather important and Apple doesn’t want it to be too easy to change them, especially if the edit is being made by a malicious app. To that end, you can no longer open these apps with TextEdit, and you need a special app for it. There are quite a few apps that you can use to edit a Plist file on macOS but the best, free option that you have is Apple’s own Xcode app.
You can download the latest, stable version of Xcode from the Mac App Store. You do not need a developer account to download the app. Your Apple ID is going to do the job just fine. Install Xcode and launch it at least once to make sure it is set up properly and then you can use it to edit a Plist file.
Edit a Plist file
Navigate to the folder with the Plist file. These files are hidden inside an app package so what you need to do is navigate to where the app itself resides. This is most likely the Applications folder but apps can run from other folders as well. Right-click the app and select the ‘Show Package Contents’ option from the context menu.
In the Folder that opens, you will see a Contents folder. Open it and inside, there should be at least one Plist file called info.plist.
Right-click it and select Open With>Xcode.
The file will open in Xcode and you can edit the already existing rows of preferences. To add a new preference, right-click a row and select the ‘Add Row’ option or the ‘Value Type’ option. You can also remove a preference by cutting it, and add one by pasting it in. It’s up to you to know what edits you can make to a Plist file, and where to make them. The contents of these files are different for each app so there is no definitive guide on what you can and cannot add. Save the changes when you’re done.
A Plist file is not something you should edit if you’re not sure you know what you’re doing. An incorrect entry can damage the app. You should also avoid editing Plist files of stock apps.