As the title says, suppose I instantiate an UIImage object with imageNamed:.. this creates and returns a pointer to an autocached UIImage object, correct?
What happens if the frameworks decides that its cache needs to be purged (for whatever reason, though most likely running low on memory) ? Do I just get stuck with a dead pointer?
edit: The reason I ask, is not that I plan to use imageName, but rather am duplicating its core functionality in my own resource management class.
I've always assumed that, if you don't retain the object +imageNamed: gives you, it's not necessarily going to be valid at any time after that initial call. Retaining it, though, seems to keep that instance alive.
It will load the new image for you. Here is the documentation:
This method looks in the system caches for an image object with the specified name and returns that object if it exists. If a matching image object is not already in the cache, this method loads the image data from the specified file, caches it, and then returns the resulting object.
As I understand it the "autocache" issue with imageNamed is that once you open an image with UIImage::imageNamed, it's cached by the system and never released. That's why Apple encourages usage of UIImage::imageWithContentsOfFile instead for images that are used occasionally. For images that are used very often in the UI, imageNamed is OK.
Your instance, while you retain it, will not be unloaded.
As long as you retain the image, it won't be purged from the cache. The caching helps if you use imageNamed again sometime before a purge and don't have anymore active pointers to the image. In this case you'll just get the image back again, without the need to have it reloaded. Apple finally exposed this functionality for us to use in our own apps with NSCache