I’ve recommended the dongsa online verb conjugator previously and the app is just as good! It provides a quick way to check you’re conjugating that difficult verb correctly, covering a wide range of possible conjugations, including past/present/future, different levels of politeness and even a few connectives.
If you select one of the conjungations it will bring up a page a truckload of further info, including conjugation rules, pronunciation and links to an internet search of the particular conjugation. The largest part of this page is the table of ‘Sentence-final forms’ – unfortunately it’s huge and a bit awkward on an iphone screen but still useful.
Dongsa is great for those quick checks when doing some writing practice and definitely worth the download (especially since it’s free!)
Available from the Apple app store