Reactive Programming with Swift 4

String protocol

Back in the days of Swift 1, Strings were a collection. In Swift 2, collection conformance was dropped because some of the behavior was thought to differ strongly enough from other collection types. Swift 4 reverses this change, so Strings are collection types again. One of the examples was described in the previous section where you were able to traverse over String vowels just like a normal array. In Swift 3, despite not being a collection, you could perform slicing operations on a String. Slicing a String in Swift 3 returned a String as well. This String was a String's own SubSequence, which led to some memory issues and one of the bigger changes in Swift 4 is the introduction of the subString types to remove these issues. ...