Cocoa-Touch: How to set the interpolation quality to be used by a UIImageView?

Question

I have a UIImageView showing a image that is larger than it's frame.
It's set to rescale the image to fit it's frame. But, the image is scaled with a low quality filter.

I've read here that this is caused by it using a low interpolation quality.

How can I get it's context to CGContextSetInterpolationQuality to kCGInterpolationHigh?

Answer 1

CGContextSetInterpolationQuality is a function. You need to call it with whatever parameters are appropriate for your situation.

http://developer.apple.com/mac/library/qa/qa2001/qa1186.html

Answer 2

UIImageView does not offer this functionality, though UIImage has an undocumented _imageScaledToSize:interpolationQuality: method if I remember correctly.

Since UIImageView draws directly to the display, subclassing and overriding drawRect: is no option (thanks to Prody for pointing this out). The only option I see is to create a custom UIView subclass with a custom drawrect: implementation.