Convert string with unknown format (any format) to date

I have data that contains a date string.

Normally it would be in a 'Jan. 3, 1966' type format, but because of international differences, it may not always be exactly that.

I need to read the data in and convert it into a standard date string ('YYYY-MM-DD').

Basically this is what I have so far:

var dataString = 'Jan. 3, 1966'  
var dateFormatter = NSDateFormatter()  
dateFormatter.dateFormat = # I DON'T KNOW THE EXACT INPUT FORMAT !
let dateValue = dateFormatter.dateFromString(dataString)  

Solution 1:

Xcode 11.4 • Swift 5.2 or later

You can use NSDataDetector as follow:

extension String {
    var nsString: NSString { self as NSString }
    var length: Int { nsString.length }
    var nsRange: NSRange { .init(location: 0, length: length) }
    var detectDates: [Date]? {
        try? NSDataDetector(types: NSTextCheckingResult.CheckingType.date.rawValue)
                .matches(in: self, range: nsRange)
            .compactMap(\.date)
    }
}

extension Collection where Iterator.Element == String {
    var dates: [Date] { compactMap(\.detectDates).flatMap{$0}
    }
}

Testing:

let dateStrings = ["January 3, 1966","Jan 3, 1966", "3 Jan 1966"]
for dateString in dateStrings {
    if let dateDetected = dateString.detectDates?.first {
        print(dateDetected)
        // 1966-01-03 14:00:00 +0000
        // 1966-01-03 14:00:00 +0000
        // 1966-01-03 14:00:00 +0000
    }
}


let dateStrings = ["January 3, 1966","Jan 3, 1966", "3 Jan 1966"]

for date in dateStrings.dates {
    print(date)
    // 1966-01-03 14:00:00 +0000
    // 1966-01-03 14:00:00 +0000
    // 1966-01-03 14:00:00 +0000
}

Solution 2:

Tested in swift 4, xcode 9

extension String {
        var detectDate: Date? {
            let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.date.rawValue)
            let matches = detector?.matches(in: self, options: [], range: NSMakeRange(0, self.utf16.count))
            return matches?.first?.date
        }
    }

Test:

print("2018-11-04T23:59:00+00:00".detectDate ?? "") // 2018-11-04 10:00:00 +0000

print("2018/11/4".detectDate ?? "") // 2018-11-04 10:00:00 +0000