Update 03/08/2019
I published a new article that shows how to improve Input Validation in Swift, using the email address validation as an example. I took the opportunity to add a small improvement, not to the NSPredicate itself, but adding a new important check to the address, related to the maximum the length.
Update 19/03/2018
Thanks to my collegues Ata Cengiz, I update the regular expression that now accepts an username with uppercase, but not a domain with uppercase.
Since the beginnig of my work experience with iOS (2010) I need to validate email format and I always used the solution proposed by Matt Gallagher in the 2009: http://www.cocoawithlove.com/2009/06/verifying-that-string-is-email-address.html
The solution is simple:
use NSPredicate to validate a String with a regular expression based on a complete verification of RFC 2822. Matt Gallagher created the Objective-C version of a previous solution that you can find here.
I wrote the Swift version and because I work, at least, on 2 projects that required to validete an email address every year, I keep update this function every time Apple update Swift. Enjoy it 🙂
