Preview App Mac Security Preferences

Preview is the default application in macOS for image files, like JPG and PNG, and PDF files. While it's primary purpose offers you a quick and easy way to see various documents, it has several pretty cool editing and markup features you may not even be know are there.

OS X's advanced filewall settings give you more control over what comes in to your Mac. The firewall is a good option to enable if you’re connected to a public Wi-Fi network, such as one at a.

How to view photos and PDFs in Preview on Mac

Preview is the default app for viewing images and PDF files on your Mac. So, any time you double-click on, or otherwise launch, one of those files, it'll open in Preview.

If, for some reason, another app has taken over responsibility for a certain file type, and you want to give it back to Preview, you make the change right in the Finder.

Right/Control - click on the file you want to open.
Hover on Open With…
Click Preview

How to crop documents in Preview on Mac

Preview can help you do some simple edit your photos and PDFs.

Open the file you want to crop in Preview.
Click the Show Markup Toolbar button. It's the button with the little toolbox icon.
Click, hold, and drag on the file to create a selection.
Click, hold, and drag on any of the blue dots to resize the selection if needed.
Use the Command - K keyboard shortcut to crop the image.

How to show markup tools in Preview on Mac

Preview has several tools to choose from to edit your photos including Selection, Sketch, Text, Color Adjust, and more. You just need to show the Markup Toolbar to see them all.

Open the file you want in Preview.
Click the Show Markup Toolbar button. It's the button with the little toolbox icon.

How to highlight PDFs in Preview on Mac

Open the PDF you want to highlight in Preview.
Click the Highlight button.
Select the text you want to highlight.
Repeat as necessary.

How to annotate a document in Preview on Mac

Preview can allow you do various different types of annotations to documents, so whether you're going through a draft of a proposal or marking papers, you can make all the notes and marks you want.

Open the file you want to annotate in Preview.
Click Tools in the top menu bar.
Hover over Annotate
Click on the type of annotation you wish to perform.

From here you have a few options of what you can do, here's a quick breakdown.

Highlight Text

Allows you to highlight any selected text.

Underline Text

Allows you to underline any selected text.

Strike Through Text

Allows you to strike through any selected text.

Rectangle

Places a rectangular on the document, which you can move around and resize.

Oval

Places an oval on the document, which you can move around and resize.

Line

Places a line on the document, which you can move around and resize.

Arrow

Places an arrow on the document, which you can move around and resize.

Polygon

Places a Polygon on the document, which you can move around and resize.

Star

Places a Star on the document, which you can move around and resize.

Text

Places a Text box on the document.

Speech Bubble

Places a Text box on the document, which you can type a message inside the bubble.

Mask

Places a layer mask on the document, so you can make a passage stand out.

Loupe

Creates a magnifying circle, perfect for calling out small icons.

Note

Creates a note, so you can leave comments.

How to add your signature to a document in Preview on Mac

If you ever type up letters or need to sign a digital contract you can save your signature in Preview and then add it to any document you want. You can add your signature using a the trackpad or even using the built-in camera.

Open the file you want to sign in Preview.
Sign your name on a piece of white paper
Click the Show Markup Toolbar button. It's the button with the little toolbox icon.
Click the Sign button.
Click Camera
Hold that **signed paper* up to the camera.
Click Done.
Click your signature.
Reposition and resize the signature to your liking

How to share documents from Preview on Mac

Open the file you want to share in Preview.
Click the Share button.
Choose the option you want. Your choices include:
- Mail
- Messages
- AirDrop
- Notes

Questions?

Anything else you'd like to know about Preview? Let us know in the comments below.

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Over the years, Apple has put its vast resources into making it's operating systems more secure for end-users. In macOS Catalina, the company has taken this to all-new levels by introducing beneficial security changes that make it even harder for miscreants to play havoc with our computers. However, because security is a tricky business, so-called improvements for some might not work for others. Specifically, Apple's decision to make Gatekeeper even more difficult crack is a significant step forward for everyday Mac users. For developers, perhaps not so much. Luckily, there's a workaround.

Warning: This terminal trick disables important security aspects of Gatekeeper, which leaves your Mac vulnerable to malware. We highly recommend you reinable the default security settings if you chose to follow this guide at your own risk.

What is Gatekeeper?

Gatekeeper has been an essential part of macOS for years. As its name suggests, the tool has been designed to check recently downloaded apps for known malware and sends it to quarantine. In his June article, The Great Mac Balancing Act, Rene Ritchie explains:

Currently, when you download an app, whether it's off the Store or the Web or even from AirDrop, that app is quarantined. If and when you try to open a quarantined app, Gatekeeper checks it for known malware, validates the developer signature to make sure it hasn't been tampered with, makes sure it's allowed to run, for example matches your settings for App Store apps and/or known developer apps, and then double checks with you that you really want to run the app for the first time, that it's not trying to pull a fast one and autorun itself.

Until now, Gatekeeper didn't take the same approach with apps launched via Terminal. It also didn't check non-quarantined apps and files for malware. In other words, it checked an app only once for malware.

Significant changes have arrived with macOS Catalina.

Now, apps started through Terminal are also checked. These files get the same malware scan, signature check, and local security policy check. The difference: even on the first run, you only need to explicitly approve software launched in bundles, like a standard Mac app bundle, not for standalone executables or libraries.

With macOS Catalina, perhaps more significantly, Gatekeeper will also check non-quarantined apps and files for problems. Not just once or twice, but every time you run it. When your Mac detects a problem, it blocks the file, then sends you an alert.

If all this sounds fantastic to you, terrific. That's undoubtedly Apple's intent. However, some developers might view this differently and find the changes cumbersome, at best.

A Workaround

Even though Gatekeeper in macOS is now stricter than ever, there is a way around it -- including macOS Catalina's newest tools. The workaround makes it possible to download and use apps downloaded from anywhere on macOS Catalina and earlier versions without a check.

First published in 2016 by OSX Daily, but still valid, the 'fix' works like this:

Be sure to exit System Preferences on your Mac.
On Finder, click Go.
Select Utilities.
Double-click Terminal.
Type of the following command syntax: sudo spctl --master-disable .
Hit Return
Authenticate with an admin password.
Hit Return.
Exit Terminal.

Changing your settings

Now, it's time to allow your Mac to open any app.

Click on System Preferences on your Mac Dock.
Choose Security & Privacy.
Tap the lock at the bottom left of the screen.
Enter your password to unlock Security and Privacy.
Choose the Anywhere under Allow apps downloaded from. Prior to making the change, this option wasn't available.
Click the unlocked lock to keep the change.

With this change, Gatekeeper no longer monitors your computer for malware coming from apps and files.

Restoring to the original setting

If you'd like to return to the default Gatekeeper settings, perform these steps:

Be sure to exit System Preferences on your Mac.
On Finder, click Go.
Select Utilities.
Double-click Terminal.
Type of the following command syntax: sudo spctl --master-enable .
Hit Return
Authenticate with an admin password.
Hit Return.
Exit Terminal.

View the change

To confirm your Mac has returned to the default settings:

Click on System Preferences on your Mac Dock.
Choose Security & Privacy.

Under Allow apps downloaded from, notice the select is now App Store and identified developers.

Should you make this switch?

Preview App For Mac

For nearly every Mac user, there's no reason to make the listed change under Security & Privacy on macOS Catalina. It should only be performed if you can quickly determine whether apps are legitimate or not. Keep this in mind.

Questions?

If you have any questions or concerns about Gatekeeper or the rest of the macOS Catalina update, let us know in the comments below.

macOS Catalina

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