Show Hidden Files in Finder

CMD+SHIFT+.
 

iOS System Icons

How do I know what images are available using systemName?
Image(systemName: "map")
 
View the Symbols: https://developer.apple.com/design/human-interface-guidelines/sf-symbols/overview/
 
Use the free tool: https://developer.apple.com/sf-symbols/
 

Create a Playground in Xcode

In Xcode 12, creating a playground isn't as obvious as it used to be.
To create a new playground, when Xcode opens, File | New | Playground
Select Blank and you're ready to go.

Creating a password protected zip file on a Mac

Open up terminal and execute the following command: zip -er MyZipFile.zip MyFileToCompress.pdf
You will be prompted for the password after hitting enter.
The MyZipFile.zip should be changed to your expected zip file being created.
The MyFileToCompress.pdf could be a folder or a group of files. Anything you want included in the zip.