NilStack · April 21, 2018 02:46 · Apr 14, 2018 · Apr 14, 2018 · Apr 13, 2018
diff --git a/UICollectionViewFlowLayout+DelegateAccess.swift b/UICollectionViewFlowLayout+DelegateAccess.swift
@@ -0,0 +1,74 @@
+
+extension UICollectionViewFlowLayout {
+
+    typealias DelegateMethod<Key, Value> = ((UICollectionView, UICollectionViewLayout, Key) -> Value)
+
+    private var delegate: UICollectionViewDelegateFlowLayout? {
+        return collectionView?.delegate as? UICollectionViewDelegateFlowLayout
+    }
+
+    func retrieve<Key, Value>(
+        using delegateMethod: DelegateMethod<Key, Value>?,
+        key: Key,
+        fallback: @autoclosure () -> Value
+    ) -> Value {
+
+        guard
+            let collectionView = collectionView,
+            let value = delegateMethod?(collectionView, self, key)
+        else {
+            return fallback()
+        }
+
+        return value
+    }
+
+    public func inset(for section: Int) -> UIEdgeInsets {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:insetForSectionAt:),
+            key: section,
+            fallback: sectionInset)
+    }
+
+    public func sizeForItem(at indexPath: IndexPath) -> CGSize {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:sizeForItemAt:),
+            key: indexPath,
+            fallback: itemSize)
+    }
+
+    public func minimumLineSpacing(for section: Int) -> CGFloat {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:minimumLineSpacingForSectionAt:),
+            key: section,
+            fallback: minimumLineSpacing)
+    }
+
+
+    public func minimumInteritemSpacing(for section: Int) -> CGFloat {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:minimumInteritemSpacingForSectionAt:),
+            key: section,
+            fallback: minimumInteritemSpacing)
+    }
+
+    public func referenceSizeForHeader(in section: Int) -> CGSize {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:referenceSizeForHeaderInSection:),
+            key: section,
+            fallback: headerReferenceSize)
+    }
+
+    public func referenceSizeForFooter(in section: Int) -> CGSize {
+
+        return retrieve(
+            using: delegate?.collectionView(_:layout:referenceSizeForFooterInSection:),
+            key: section,
+            fallback: footerReferenceSize)
+    }
+}