Make verticalLayoutDirection configurable after initialization (#146)

Author: bryankeller

MagazineLayout/Public/MagazineLayout.swift

@@ -30,24 +30,21 @@ public final class MagazineLayout: UICollectionViewLayout {
   ///   - flipsHorizontallyInOppositeLayoutDirection: Indicates whether the horizontal coordinate
   ///     system is automatically flipped at appropriate times. In practice, this is used to support
   ///     right-to-left layout.
-  ///   - verticalLayoutDirection: The vertical layout direction of items in the collection view. This property changes the
-  ///   behavior of scroll-position-preservation when performing batch updates or when the collection view's bounds changes.
-  public init(
-    flipsHorizontallyInOppositeLayoutDirection: Bool = true,
-    verticalLayoutDirection: MagazineLayoutVerticalLayoutDirection = .topToBottom)
-  {
+  public init(flipsHorizontallyInOppositeLayoutDirection: Bool = true) {
     _flipsHorizontallyInOppositeLayoutDirection = flipsHorizontallyInOppositeLayoutDirection
-    self.verticalLayoutDirection = verticalLayoutDirection
     super.init()
   }
 
   required init?(coder aDecoder: NSCoder) {
     _flipsHorizontallyInOppositeLayoutDirection = true
-    verticalLayoutDirection = .topToBottom
     super.init(coder: aDecoder)
   }
 
   // MARK: Public
+  
+  /// The vertical layout direction of items in the collection view. This property changes the behavior of
+  /// scroll-position-preservation when performing batch updates or when the collection view's bounds changes.
+  public var verticalLayoutDirection = MagazineLayoutVerticalLayoutDirection.topToBottom
 
   override public class var layoutAttributesClass: AnyClass {
     return MagazineLayoutCollectionViewLayoutAttributes.self
@@ -844,7 +841,6 @@ public final class MagazineLayout: UICollectionViewLayout {
   // MARK: Private
 
   private let _flipsHorizontallyInOppositeLayoutDirection: Bool
-  private let verticalLayoutDirection: MagazineLayoutVerticalLayoutDirection
 
   private lazy var modelState: ModelState = {
     return ModelState(currentVisibleBoundsProvider: { [weak self] in

Tests/ContentInsetAdjustingContentOffsetTests.swift

@@ -19,7 +19,7 @@ import XCTest
 final class ContentInsetAdjustingContentOffsetTests: XCTestCase {
 
   func testContentOffsetIsNotAdjustedForTopInsetChangeWithToTopBottomLayout() {
-    let layout = MagazineLayout(verticalLayoutDirection: .topToBottom)
+    let layout = MagazineLayout()
     let collectionView = StubCollectionView(
       frame: .zero,
       collectionViewLayout: layout)
@@ -33,7 +33,8 @@ final class ContentInsetAdjustingContentOffsetTests: XCTestCase {
   }
 
   func testContentOffsetIsAdjustedForTopInsetChangeWithBottomToTopLayout() {
-    let layout = MagazineLayout(verticalLayoutDirection: .bottomToTop)
+    let layout = MagazineLayout()
+    layout.verticalLayoutDirection = .bottomToTop
     let collectionView = StubCollectionView(
       frame: .zero,
       collectionViewLayout: layout)
@@ -47,7 +48,8 @@ final class ContentInsetAdjustingContentOffsetTests: XCTestCase {
   }
 
   func testContentOffsetIsAdjustedForBottomInsetChangeWithBottomToTopLayout() {
-    let layout = MagazineLayout(verticalLayoutDirection: .bottomToTop)
+    let layout = MagazineLayout()
+    layout.verticalLayoutDirection = .bottomToTop
     let collectionView = StubCollectionView(
       frame: .zero,
       collectionViewLayout: layout)
@@ -61,7 +63,8 @@ final class ContentInsetAdjustingContentOffsetTests: XCTestCase {
   }
 
   func testContentOffsetIsAdjustedForTopAndBottomInsetChangesWithBottomToTopLayout() {
-    let layout = MagazineLayout(verticalLayoutDirection: .bottomToTop)
+    let layout = MagazineLayout()
+    layout.verticalLayoutDirection = .bottomToTop
     let collectionView = StubCollectionView(
       frame: .zero,
       collectionViewLayout: layout)