Don't upgrade
The free version works well as far as it goes, but when I tried another filter I was required to upgrade to the pro version to access it--that would also have removed the annoying ads. However, having paid the £2-99, my screen showed a continuous 'Loading' message and nothing more happened. I clicked on the developer website link in the app details in App Store--this gave a page 'This domain may be for sale'. So there is no way to contact the developer. It remains to be seen whether I have lost my money or not. I think that Apple should be re-examining this app. Meanwhile, best to avoid it.
