Custom String extension of Swift to compare versions in String.

CompareVersion.swift

extension String {
  
  // Compare iOS version in Swift
  // Version format "12.34.39" where "12" is "Major", "34" is "Minor" and "39" is "Bug fixes"
  // "maximumDigitCountInVersionComponent" is optional parameter determines the maximum length of "Major", "Minor" and "Bug Fixes" 
  func shouldUpdateAsCompareToVersion(storeVersion: String, maximumDigitCountInVersionComponent: Int = 5) -> Bool {
        let adjustTralingZeros: (String, Int)->String = { val, count in
            return "\(val)\((0..<(count)).map{_ in "0"}.joined(separator: ""))"
        }
        let adjustLength: ([String.SubSequence], Int)->[String] = { strArray, count in
            return strArray.map {adjustTralingZeros("\($0)", count-$0.count)}
        }
        let storeVersionSubSequence = storeVersion.split(separator: ".")
        let currentVersionSubSequence = self.split(separator: ".")
        let formatter = NumberFormatter()
        formatter.minimumIntegerDigits = maximumDigitCountInVersionComponent
        formatter.maximumIntegerDigits = maximumDigitCountInVersionComponent
        let storeVersions = adjustLength(storeVersionSubSequence, maximumDigitCountInVersionComponent)
        let currentVersions = adjustLength(currentVersionSubSequence, maximumDigitCountInVersionComponent)
        var storeVersionString = storeVersions.joined(separator: "")
        var currentVersionString = currentVersions.joined(separator: "")
        let diff = storeVersionString.count - currentVersionString.count
        
        if diff > 0 {
            currentVersionString = adjustTralingZeros(currentVersionString, diff)
        }else if diff < 0 {
            storeVersionString = adjustTralingZeros(storeVersionString, -diff)
        }
        let literalStoreVersion = Int(storeVersionString)!
        let literalCurrentVersion = Int(currentVersionString)!
        return literalCurrentVersion < literalStoreVersion
    }
}