Glyphs and Images
There are several opportunities to use small, expressive images in your watchOS app, complications, and notifications. In most cases, you use a glyph — also known as a template image — which is a monochromatic image with transparency, antialiasing, and no drop shadow that uses a mask to define its shape. SF Symbols provides a comprehensive selection of symbols you can use as-is or to create a custom symbol. If necessary, you can also design your own template images.
When the system displays a glyph, it generally applies the accent color your app supplies. In watchOS 6 and later, the glyphs you supply for graphic family complications get tinted according to the wearer’s color selection. For guidance, see Complications.
Provide glyphs as autoscaling PDFs. Size the glyph for the 40mm and 42mm devices; the system automatically scales your glyph for the 38mm and 44mm devices (see Autoscaling PDF Images). Otherwise, provide separate PNGs for each device. Avoid using interlaced PNGs.
Set line thickness to two points or greater to ensure legibility. If you design your own template images, be sure to use line weights that are appropriate for the device size and the complexity of the glyph. For a downloadable guide to menu glyphs, see Apple Design Resources.