iOS: Self Control made a name for itself for being serious about blocking out distractions — you couldn't just turn the app off, or reboot your computer, to make it go away. Now, an app inspired by the original has landed on the iPhone, offering a similar no-nonsense approach to keeping you focused on what's important.
Self Control for iPhone isn't affiliated with, or the same team behind the original Self Control for Mac, but the developer was inspired by the original for his iPhone version. It operates the same way though — just add any domain or URL to the app's blacklist, and then when you save it, it will block those pages in Safari with a simple error message that says the page has been blocked by a content blocker.
Of course, the iPhone version isn't quite as no-nonsense as the desktop version. You can, any time you want, remove a blocked page from Self Control and it will display again. It will ask you if you're sure, giving you that moment of pause needed to stop and think about whether you have something better to be doing right now than reading whatever it is you're about to unblock, but once it's unblocked, you're free to do what you want. Similarly, you can disable Self Control entirely whenever you want to. On the other hand, there are no time limits: Once you add a site to Self Control, it's blocked until you remove it.
The app is a little drastic, but depending on how hard a time you have focusing, or if you have a bad habit of being glued to your phone when you should be doing other things, this might help give you the push you need to break that habit. The app is three bucks, hit the link below to check it out.