IOS – Clear iOS Safari icon cache

On iOS, HTML5's local storage is not available in private browsing mode, which means you can detect it by attempting to save something to local storage and catching the exception with the following JavaScript:

try { localStorage.test = 2; } catch (e) {
  alert('You are in Private Browsing mode');
}

^{Modified from https://stackoverflow.com/a/17741714/}

On OS X, there's not really a canonical method, but this should provide some useful information:

• Can web sites detect whether you are using private browsing mode? –Security.SE

If you're looking for implementation guidance, you should probably try Stack Overflow instead

I was having this same issue. Try deleting the Library/Safari/Touch Icons/ folder

After that, relaunch Safari and it should download them all again. This worked for most of my icons with the exception of the websites that don't have any custom icons available.