Question: How to properly clear cache?

Hi @daniel-luberda

I need your help to understand how to clear cache in some specific cases? here is my scenario

I have mainpage with 3 horizontal listviews with each datetemplate has CacheImage as CacheType Memory implemented. when i profile after main page is loaded, I reach to 100mb memory usage although I am using Downsampling correctly I believe. If I remove lists I experience around 50mb. I can even accept 100mb for mainpage but my problem starts after I navigate to page 1 with a single listview with images it increases to 120 mb. How can I dispose or get rid off images loaded on Mainpage? I tried to set null ItemsSource each listview in OnDisappearing method of the mainpage but it didnt help at ll?

protected override void OnDisappearing()
     {
         base.OnDisappearing();

         // in order keep memory usage lower
         listview1.ItemsSource = null;
         listview2.ItemsSource = null;
         listview3.ItemsSource = null;
        
     }

[daniel-luberda]

FFImageLoading manages memory usage automatically, you shouldn’t worry about anything in most scenarios. If you exceed MaxMemoryCacheSize (configurable), it automatically removes bitmaps that are least used from memory, the rest is managed by OS. You shouldn’t worry about memory usage until loading some huge amounts of images or some big size images.

If you still want manually remove an entry from cache you can easily do that with:

await ImageService.Instance.InvalidateCacheEntryAsync("image.png or http://something", Cache.CacheType.Memory, removeSimilar: true);

But I advise you to not do that as it isn’t necessary.

[daniel-luberda]

if I use cachetype memory, does it make sense to use CacheDuration, once i exit the app, memory cache will be release I guess.

In that case this is ignored as no disk cache is involved.

I expect that page is disposed. but if there is cached image in the memory, page might be still in the memory and never disposed. Have you ever checked this with a profiler.

It’s not how it works. Bitmaps are not related to the Xamarin.Forms at all, they’re strictly native objects and OS manages them automatically. Page will be disposed without any issues, but the bitmap would be cached so it could be loaded faster for other image loading tasks. FFImageLoading uses LRU memory cache, so only most used bitmaps are cached, others are freed if memory usage is to high.