Question

im pulling in images from the net, and want to manipulate them a bit such as adding perspective with CATransform3D, and compositing a couple together. After im done, I would like to save the file in memory so they can be pulled up when needed (like in a tableview cell for example). I managed to extract the image from the web, and manipulate them by making a CALayer. After a bit of reading, im a bit confused as to how to properly do this since these images arent displayed until needed and I obviously would like to do my work on a worker thread so the system wont lag. What would the best procedure be?

Answer 1

Apple recommends that you almost never try to cache images yourself since they cache them internally and you can be guaranteed that the cache will function properly even under high memory pressure.

You can cache an image using Apple’s internal cache via the setName: and imageNamed: methods`. Furthermore, you should save a local copy of the image to disk in the caches directory so you dont need to download it again if the cache gets cleared.

So, in summary, use imageNamed:, if that is nil check the disk cache directory, if that is nil download the image. Caching a CALayer will make sooo much dirty memory,