An image view displays a single image or an animated sequence of images over a transparent or opaque background. Within an image view, images may be stretched, scaled, sized to fit, or pinned to a specific location. Image views are noninteractive by default.
If possible, ensure that all images within an image view are consistently sized. If your images are different sizes, the image view adjusts them separately. Using consistently sized images is more efficient than using images of varying size. It’s even more efficient to use images that are prescaled and don’t require any adjustments.
For developer guidance, see UIImageView.