That was done without code. All I did was to configure the SVG in the asset catalog to have a single size and to preserve vector data:

That is completely different from what you're doing; you are drawing the SVG into a graphics context, so you are throwing away the vector data and substituting a bitmap, which of course does not scale perfectly.

CodePudding user response：

Not pretending to give a full answer, just a few ideas:

1. Please check this nice tutorial which explains the need of using .interpolation(.none) in such cases for SwiftUI.Image.
2. Don't resize the UI image - resize only SwiftUI image, as now you know a very simple way to deny interpolation.
3. If the step 2 won't work (e.g. no transparency(alpha channel) or some other problems), probably you'll have to pre-process that UIImage with CoreGraphics (this is definitely not performant, but may look good).
4. In the worst-case scenario, you'll have to implement that UIImage.resize function using CGContext, paying attention to the interpolation quality.

So, the main ideas are:

1. You tried UIGraphicsImageRenderer, but there still are a lot of other options to explore, and you should check them one-by-one to get some intuition of what works and what doesn't.
2. Your resized image looks blurry, so the main issue is probably with the interpolation (mixing a neighbouring pixels' alpha channel when you downscale), so you should deny the interpolation. You can investigate how to fix the performance issues once everything is rendered well.