A strategy emerged on how to process MaxMindDB data. May not be the best, but it could work.

Signed-off-by: Adam Rocska <adam.rocska@adams.solutions>

Sources/MaxMindDBReader/MaxMindIterator.swift

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+//
+// Created by Rocska Ádám on 2020. 05. 04..
+//
+
+import Foundation
+
+class MaxMindIterator {
+  private let data:    Data
+  private var pointer: Data.Index
+
+  init?(_ data: Data) {
+    if data.isEmpty { return nil }
+    self.data = data
+    self.pointer = data.startIndex
+  }
+
+  func nextControlByte() -> ControlByte? {
+    return nil
+  }
+
+}

Tests/MaxMindDBReaderTests/MaxMindIteratorTest.swift

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+import Foundation
+import XCTest
+@testable import MaxMindDBReader
+
+class MaxMindIteratorTest: XCTestCase {
+
+  func testInit_returnsNilIfDataIsEmpty() {
+    XCTAssertNil(MaxMindIterator(Data()))
+  }
+
+  func testNextControlByte_noneDefined() {
+    let iterator = MaxMindIterator(Data(count: 150))
+    for _ in 0..<200 {
+      XCTAssertNil(iterator?.nextControlByte())
+    }
+  }
+
+}