Is there a general guideline or rule of thumb on when I should cache a photo?
For example I have a grid view of smaller icon images. This page isn't at the beginning of the app so there's no guarantee a user sees it, these images could change server-side but for the most part they won't. Should I cache them because there are so many or not worry about them because they are small?
Another example would be if I click on one of the images mentioned above it will lead me to a view with one larger image, should I cache this image since it's larger or should I let the user make a network request each time?
I'm not looking for an answer for these specific questions, but rather a guideline to follow.
To clarify by caching I mean saving the file to storage. Also, is there a better method than this?
Thanks for the help!
Caching is an important feature in user experience, so even if there's no guarantee the user sees that particular 'page', it a nice thing to have.
Saving images in a cache depends directly on many variables:
- How much time does it take to regenerate images if not cached
- How many images are we talking about
- How often do they change
- What size is each image
For example, having 100 thumbnails of images that change every month makes a lot of sense. Caching 200 images with 1024x768 resolution that change very often doesn't.... or does it? The answer is very variable.
Also cache should always have storage boundaries. Even in the previous example with the large images, you could limit the cache to a a certain storage capacity.
Normally the cache saves a local copy of the most recently used items. But you can implement a more sophisticated algorithm, for example, saving the most visited images instead of caching the most recently used.