Syncany is not available for iPhone but there are plenty of alternatives with similar functionality. The best iPhone alternative is Nextcloud, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Syncany and many of them is available for iPhone so hopefully you can find a suitable replacement. Other interesting iPhone alternatives to Syncany are Dropbox (Freemium), Google Drive (Freemium), Microsoft OneDrive (Freemium) and Cryptomator (Freemium, Open Source).
You should have full control over your data. We help you achieve that: a safe home for all your data. Secure, under your control and developed in an open, transparent and trustworthy way. We are Nextcloud.
Cryptomator provides transparent, client-side encryption for your cloud. Protect your documents from unauthorized access. Cryptomator on the desktop is free and open source software, so you can rest assured there are no backdoors.