Is Trying to index into String really hard?

Paul Hudson published a great book called Swift Coding Challenges which I highly encourage you to buy it and dig into it. But head back to the question. Paul said:

This is one of the most common interview questions you’ll come across, and it has a particular quirk in Swift that might have caught you out: strings might look like arrays, but trying to index into them is hard.

Since Swift 2,String does no longer conform to SequenceType.In other words, you can not iterate through a string with a for...in loop.In this article, we’ll know trying to index into string is realy hard or no, and what are the options that you can use to trade-off this issue, and how to fix this issue easily without any conversion.