The new sidecar function in macOS Catalina extends the display of your Mac to your iPad. This allows you to use your iPad as a secondary monitor or as a mirrored screen that works with Apple Pencil and accessories such as a mouse and keyboard.
How Sidecar works
Once you have macOS Catalina installed on your Mac, you can connect your iPad to your computer and use it as an external screen. It works in both a wired and wireless mode.
If you connect your iPad via a USB-C or Lightning cable, the connection will be faster and more stable. But for most users, the wireless connection works just as well. There is no major delay because Apple uses its own Wi-Fi-based AirDrop-like peer-to-peer connection.
Due to the peer-to-peer connection, Sidecar only has a reach of 10 feet. When you move to another room, you notice a delay and a warning on the screen asking you to get closer to the Mac.
If you want to use the iPad as a portable screen for a Mac in your house, you must look at Luna Display that works on a Wi-Fi network and has a greater range.
Once Sidecar is turned on, the iPad works as more than just a monitor. You will see a sidebar with controls and shortcuts, along with a virtual Touch Bar at the bottom of the screen. You can use touch, Apple Pencil and a mouse to control the Mac screen on your iPad.
Although the touch UI works, it is not intuitive. If you hoped that Sidecar would turn the Mac into an iPad where you can tap and move your fingers on the screen, unfortunately this is not it. The UI elements in Mac were rather small for this.
So if you tap the screen with a finger or try to scroll with a finger, nothing happens. You must use two fingers to browse. And the only way to click or tap on elements is by using the Apple Pencil or a mouse connected to the iPad (causing a cursor to appear on the screen). The keyboard and trackpad of the Mac naturally work reliably.
The Apple Pencil can also not be used to navigate through the user interface. It can only be used for clicking and selecting things on the Mac. Apple Pencil shines when it is used to draw on the screen in supported apps. This works natively for the Mark Up feature in Preview, along with third-party apps such as Affinity Photo, Adobe Illustrator, etc.
What this means is that you have to use Sidecar as a second screen, you have to get used to a new interaction model . Swipe with two fingers to navigate, click and select with Apple Pencil or a mouse. The new text selection and editing gestures of iOS 13 and iPadOS 13 also work here.
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Sidecar function is supported on the following macs with macOS Catalina:
- MacBook Pro introduced in 2016 or later
- MacBook introduced in 2016 or later
- MacBook Air introduced in 2018 or later
- iMac introduced in 2016 or later, plus iMac (Retina 5K, 27-inch, end of 2015)
- iMac Pro  Mac mini introduced in 2018 or later
- Mac Pro introduced in 2019
And on the following iPads with Apple Pencil support with iPadOS 13:  iPad Pro: all models
Before using Sidecar, make sure that both devices are connected to the same Wi-Fi network and that Bluetooth and Wi-Fi are enabled on the bot h devices
Side set up car
The connection process with Sidecar is the same for both wired and wireless connections. If you are going to use the wired connection method, first connect the Mac to your iPad with a compatible cable.
You can start the Sidecar connection in different ways. The best way is to use the AirPlay option in the menu bar.
If you cannot find the AirPlay icon in the menu bar, you can turn it on by going to System Preferences> Displays and selecting "Show mirror options in the menu bar if available".
Now click on the "AirPlay" button in the menu bar. Select your iPad here.
And that's all. The Sidecar function is now switched on and your iPad starts to work as an external display. You can now drag and drop windows from your Mac screen to the iPad.
Alternatively, you can go to System Preferences> Sidecar and then click on the "Select Device" drop-down list and select your iPad from the list. Sidecar should now run on your iPad.
Using and Adjusting Sidecar
Although you can easily use the iPad as a second monitor, there are some specific macOS controls to enhance your experience.
First of all, you can switch to mirror mode to control the Mac from the iPad. This can be useful if you stay in the room but are not behind the computer.
To do this, click on the "Sidecar" button in the menu bar after the iPad is connected. Then click on "Mirror built-in Retina display."
The user interface of Sidecar on the iPad is fairly simple. On the right you see a sidebar and a virtual Touch Bar at the bottom (even if your Mac doesn't support Touch Bar).
At the top of the sidebar, you will find options to show or hide the menu bar and the Dock so that you can enable full screen mode on the Mac.
In the middle you will find your modification keys: Command, Option, Control and Shift. You can double-tap a key to lock it.
At the bottom you see the Undo, Keyboard, and Disconnect options.
The "Keyboard" button brings up the compact floating keyboard of iPadOS that supports typing gestures. You can use the "Disconnect" button to end the Sidecar connection.
You can also customize the Sidecar user interface on the iPad. On your Mac, go to System Preferences> Sidecar.
From here, use the drop-down list next to "Show sidebar" to move the sidebar from left to right. You can also move the Touch Bar up or down from the "Touch Touch Bar" option.
In addition, you can disable the "Show Sidebar" and "Show Touch Bar" options to disable both elements.
If you are an avid Apple Pencil user, you can also check the "Enable Apple Pencil Double-click" option to use the double-tap gesture as a right-click option on the Mac.
To disconnect the Sidecar, select the "Disconnect" button at the bottom right or bottom left (depending on your preferences) on the iPad screen.
Alternatively, from the menu bar on your Mac, go to the "AirPlay" menu and click on the "Disconnect" button.