Open Radar

 
Summary:
On iOS 11, UIImageView sometimes renders its image rasterized even when the image as `preserves-vector-representation` set to `true` in the assets catalog.

This occurs when the UIImageView has less than 3 "Spacing to nearest neighbor" autolayout constraints.

Steps to Reproduce:
1. Add a new image to your asset catalog
2. Set the image resizing mode to "Preserve Vector Data" (check the checkbox)
3. Add a UIImageView to a storyboard / nib, and set its image to the image added in step 1
4. Position the UIImageView with at most 2 "spacing" constraints
   (For example, a Vertical Spacing to Top, a Horizontal Spacing to Left, a Width, and a Height constraints)

Expected Results:
Regardless of the original image file size, the UIImageView renders the crisp, non-aliased version of the image, based on the vector data.

Actual Results:
The image is rendered as if the `preserves-vector-representation` property was set to false, with a rasterize version of the image enlarged to fit the UIImageView size. The result being a scale-up, blurry, aliased image.

Version:
11.0 beta 9 (15A5370a)

Notes:
Attached is a minimal sample project exhibiting the bug. The 2nd-to-top image has only 2 "spacing" constraint and is blurry, the bottom one has 3 "spacing" constraint and is crisp.

This is probably related to rdar://34279759 (http://www.openradar.me/radar?id=5005434293321728), as the conditions to reproduce the bug are the same.

Related SO question, were I discuss the bug with Matt Neuburg: https://stackoverflow.com/questions/45622894/