See Also: UIImage Members
To avoid issues with excessive memory use, UIImages objects should not be larger than 1024x1024 in size. Code-based manipulations such as resizing are not subject to this restriction.
It is possible that the system may purge UIImage objects to free up memory. If the UIImage is required later on by an application, it will be loaded again from its source file.
The following image formats are supported by the UIImage class:
Starting with iOS 8, the MonoTouch.UIKIt.UIImage.FromBundle(string, MonoTouch.Foundation.NSBundle, MonoTouch.UIKIt.UITraitCollection) method can be used to load a UIImage that takes into consideration a MonoTouch.UIKit.UITraitCollection. This can automatically load the proper image for the specified resolution.
Most of the members of this class can be used from a background thread, with a couple of exceptions (FromBundle methods that retrieve images from the bundle and use the built-in memory cache).