Parsing a Swift String to Date, then Components

Question

I have a date "2017-12-31" as a String.

What I want to get finally is only the month: "12" as a String.

So I thought that I can change it to Date using a date formatter

let formatter = DateFormatter()
formatter.dateFormat = "MM"

What do I do next?

Answer 1

First you have to use the DateFormatter to create a temporary Date object from your source String object. Then you have to use it to create your final String from the temporary Date object.

let dateString = "2017-12-31"
let dateFormatter = DateFormatter()

// set the dateFormatter's dateFormat to the dateString's format
dateFormatter.dateFormat = "yyyy-MM-dd"

// create date object
guard let tempDate = dateFormatter.date(from: dateString) else {
    fatalError("wrong dateFormat")
}

// set the dateFormatter's dateFormat to the output format you wish to receive
dateFormatter.dateFormat = "LL" // LL is the stand-alone month

let month = dateFormatter.string(from: tempDate)