Convert iOS version string into number - Swift

gistfile1.txt

// Why do you want a numeric version? Because number format is easier to use than string.
// For example, you may want to write a NSPredicate for Core Data fetch for different version:
// NSPredicate(format: "clientVersionNumber < %@", "2070500") // 2.7.5
// This gist assume the version digit is limitted to 4.

public static var versionString: String {
    return (Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String) ?? "1.0"
}

// Only support 4 digits, invalid string will return 0, longer digits will be dropped
// 3.2.2.1 -> 3020201, check testVersionNumber() for examples
public static func versionNumber(from version: String?) -> Int32 {
    guard let version = version else {
        return 0
    }
    var result = ""
    let limitDigit: Int = 4
    let versionSplit: [Int] = Array(version.split(separator: ".").map { Int($0) ?? 0 }.prefix(limitDigit))
    let versionDigits: [Int] = versionSplit + Array(repeating: 0, count: max(limitDigit - versionSplit.count, 0))

    assert(versionDigits.count == limitDigit)

    let formatter = NumberFormatter()
    formatter.maximumIntegerDigits = 2
    formatter.minimumIntegerDigits = 2
    versionDigits.forEach { d in
        result.append(formatter.string(from: d as NSNumber) ?? "00")
    }

    return Int32(result) ?? 0
}

func testVersionNumber() throws {
    XCTAssertEqual(BaseManagedObject.versionNumber(from: "2.1"), 2010000)
    XCTAssertEqual(BaseManagedObject.versionNumber(from: "3.1.2"), 3010200)

    XCTAssertEqual(BaseManagedObject.versionNumber(from: "3.2.2.1"), 3020201)
    XCTAssertEqual(BaseManagedObject.versionNumber(from: "3.2.2.1.1"), 3020201)

    XCTAssertNotEqual(BaseManagedObject.versionNumber(from: "3.2.2"), 3020201)

    XCTAssertEqual(BaseManagedObject.versionNumber(from: "mess"), 0)
    XCTAssertEqual(BaseManagedObject.versionNumber(from: ""), 0)
    XCTAssertEqual(BaseManagedObject.versionNumber(from: nil), 0)
    XCTAssertEqual(BaseManagedObject.versionNumber(from: "1"), 1000000)
}