Sidecar: the iPad becomes an external screen of the Mac

In the MacOS Catalina small news series, here is Sidecar. No, we're not going to talk about motorcycles, even if Apple sticks wheels to the Mac Pro^{. Sidecar allows you to use the iPad as an external display, like Duet Display or Luna Display, and even as a graphics tablet with the Apple Pencil. A strange hitch, which blurs the boundaries between different devices, but is surprisingly useful.}

Have you ever manipulated your Mac's screen from your iPad, using an app like Screens? You may have used, perhaps unwittingly, a VNC connection. Well Sidecar … is not a VNC connection. Sidecar is rather an extension of the AirPlay monitor: it can not be activated from the iPad that you want to use as a screen, but must be activated from the Mac you want to deport the display.

In other words, Sidecar will not replace Screens to control a mini Mac hidden in a closet. But it can replace Duet Display to extend the display of a MacBook Pro on your desktop. If your MacBook Pro is compatible with this new feature, at least. Only the most recent machines, those whose graphics chips are able to encode a HEVC stream, are compatible with Sidecar:

• MacBook since the model early 2016;
• MacBook Air 2018;
• MacBook Pro since the 2016 model;
• Mac mini 2018;
• iMac 27 "since the model at the end of 2015;
• iMac Pro 2017;
• and the 2019 Mac Pro.

A command line enable Sidecar on some older models – but since the processor will have to handle the display, get ready to hear the fans, and especially to pounce on slowdowns. In this case, we advise you to use the small dongle of Luna Display, which keeps its interest by offering similar functions without putting the processor flat.

Since it derives from the AirPlay monitor, Sidecar works with, but also without cable. According to our first tests, conducted with a MacBook Pro 15 "first connected to an iPad Pro 12.9" and an iPad 6, it is better to use a cable. The connection is more stable, the display is more fluid, and the iPad is recharged in pbading.

But Sidecar is not just an AirPlay monitor, and the iPad is not just an external monitor, which can copy or extend the Mac's display. The screen is framed by two bars:

• a sidebar, left or right according to your preferences, which makes the controls fall under the thumb. In the center, the modifier keys (⌘, ⌥, ^ and ⇧, which you can lock to chain shortcuts with a double tap). At the bottom, a shortcut Cancel, a button to open or close the virtual keyboard, and a button to close the Sidecar session. Finally a top, a very convenient button in extended mode, which displays the Dock on the screen of the iPad.
• a horizontal bar, up or down according to your preferences, which is nothing but the Touch Bar. When positioned at the bottom, its handling is particularly pleasant, since it adds a touch esc and a row of function keys on the Smart Keyboard.

The iPad can be used as any external screen, with the keyboard and trackpad of the Mac. But it can also be used (almost) as a MacBook touch: the Smart Keyboard or the virtual keyboard to type, two fingers to scroll as on the trackpad, and the Apple Pencil to point and click. The only limit is that you can not manipulate the elements directly, but the macOS interface does not lend itself to it.

Since the Apple Pencil is managed as a mouse, all applications are "compatible" with Sidecar. Graphic design application developers can, however, use Tablet Events to manage the pressure and orientation of the Apple Pencil, and even badign functions to the "double tap" on the pen body. The following applications are a good example of this advanced support, which turns the iPad into a graphics tablet:

• Affinity Designer;
• Affinity Photo;
• Cinema 4D;
• CorelDRAW
• DaVinci Resolve;
• Final Cut Pro;
• Illustrator;
• Maya;
• motion;
• Painter;
• principle;
• Sketch;
• Substance Designer;
• Substance Painter;
• ZBrush.

While you are using the iPad as a screen, iOS continues to run in the background. This causes some floating moments: when you receive a message for example, you will see two notifications, that of the Mac through Sidecar and that of the iPad. Apple must be able to optimize the operation of Sidecar, after all, macOS Catalina and iPadOS 13 will not be finalized until this fall.

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