Previewing at 1 to 1 scale
When working on a project for a touch interface, screen design should be reviewed at the size it will be displayed at, on device. This is important to correctly assess text legibility, and dimensions of tappable areas.
While designing in Sketch, setting the document's zoom level at 100% does not necessarily display your work at the size it will be viewed at by users. The Sketch Mirror app was a great way - when it functioned as intended - to have a high fidelity preview in your hands while working on an iPhone app project. But the new iOS Sketch app now requires the files you want to preview to be stored in your online Workspace. So previewing on device is not possible anymore if you like to keep things local.
I'm sharing here the solution I came up with years ago, and still use daily: a symbol that I've sized in a way that when I select it and "zoom to selection", the artboards are displayed at the correct scale. Maybe you'll learn about it, maybe you'll let me know of a better way. Here is how to set it up.
- Cut a sheet of paper to the actual width of the device's screen you want to replicate, lay it on your screen (without touching it of course).
- Open Sketch, make sure the document window is displayed at full height.
- Add an artboard at the device's dimensions.
- Beside the artboard, draw a rectangle and select it.
- Press ⌘+2, shortcut for the "Selection" menu item found in "View > Zoom To".
- Compare the width of the paper to the width of the artboard by superposing the two.
- If the artboard width is larger than the paper's, increase the rectangle's height. If it's smaller, decrease it.
- Go to 5 until both dimensions seem identical.