While trying to migrate some code from ArcGIS 10.2.5 to ArcGIS 100, I've noticed some AGSPictureMarkerSymbol changes. When creating a AGSPictureMarkerSymbol with a local asset, it takes into consideration the image size (e.g. if @2x images are provided, the symbol is using that).
However, when using programatic images (e.g. UIViews screenshots), the supplied image is treated as @1x image. On iPad 2, it's rendered at 1x, on iPad Air 2s it's rendered at 2x.
The old SDK (and Apple's UIKit) is treating the UIView "screenshot" as "fit for current size", e.g. the image is rendered at the same relative size (1x or 2x).
See attached screenshots (please ignore E66).