One of the built-in features of iOS can easily block specific phone numbers on the iPhone. When a phone number is blocked, it prevents incoming voice calls, messages and FaceTime from getting through. Mail senders can also be blocked, with the Mail app recognizing blocked email addresses and ignoring them.
Email and Messaging
For some time, iOS has made it possible to hide alerts on a Messages thread. This can be useful when a slew of text messages comes in, and you need the iPhone to remain quiet. Similar to hide alerts, Apple has added a mute function to email threads on the iPhone, iPad and iPod touch.
Update (06/14/19): Verizon has rolled out a new spam/robocalls blocking tool called "Verizon Call Filter." This new feature alerts Verizon customers to to incoming spam calls and allows them to report and block unwanted numbers. Depending on your device, you will see "a name, a picture, city and state when you receive an incoming call, text or voicemail from an unknown number." Click the link above for a Verizon Call Filter guide.
Whether you need specific symbols for a technical paper or are simply looking to add some flavor to your social media posts, the iPhone keyboard doesn't have a very extensive library of symbols. You can find a few extra symbols by long pressing on certain keys like the '$' which will reveal a few other currency symbols, and you can find some in the emoji library like the trademark and copyright symbols, but they aren't really ideal (they don't appear as superscripts).
There are any number of reasons that you may want to save an entire Message thread - perhaps you will need it for legal purposes, maybe you want to keep it for memories. Whatever the case may be, there are a few methods you can employ to save snippets of text conversations or entire conversations if they are relatively short. Unbelievably, however, Apple has not developed a simple way to export a long text conversation - your best bet is to use third-party software like Chatology.