add insert(views:) method variants (#10)

Author: JohnEstropia

StackScrollView-Demo/ViewController.swift

@@ -90,13 +90,14 @@ class ViewController: UIViewController {
     views.append(MarginStackCell(height: 40, backgroundColor: marginColor))
 
     views.append(HeaderStackCell(title: "ButtonStackCell", backgroundColor: marginColor))
-    
-    (0..<3).forEach { _ in
-      
-      let s = fullSeparator()
-      
+
+    let makeRemovableButton: () -> [UIView] = {
+
+      let s = self.fullSeparator()
+
+      var views: [UIView] = []
       views.append(s)
-      
+
       views.append({
         let v = ButtonStackCell(buttonTitle: "Remove")
         v.tapped = { [unowned v] in
@@ -105,8 +106,28 @@ class ViewController: UIViewController {
         }
         return v
         }())
-      
+      return views
     }
+
+    views.append(contentsOf: { () -> [UIView] in
+      let s = fullSeparator()
+      let v = ButtonStackCell(buttonTitle: "Insert Before")
+      v.tapped = { [unowned stackScrollView, unowned s] in
+        let views = (0 ... .random(in: 1 ... 2)).flatMap { _ in makeRemovableButton() }
+        stackScrollView.insert(views: views, before: s, animated: true)
+      }
+      return [s, v]
+      }())
+
+    views.append(contentsOf: { () -> [UIView] in
+      let s = fullSeparator()
+      let v = ButtonStackCell(buttonTitle: "Insert After")
+      v.tapped = { [unowned stackScrollView, unowned v] in
+        let views = (0 ... .random(in: 1 ... 2)).flatMap { _ in makeRemovableButton() }
+        stackScrollView.insert(views: views, after: v, animated: true)
+      }
+      return [s, v]
+    }())
 
     views.append(fullSeparator())
 

StackScrollView/StackScrollView.swift

@@ -112,6 +112,56 @@ open class StackScrollView: UICollectionView, UICollectionViewDataSource, UIColl
   func append(lazy: @escaping () -> UIView) {
 
   }
+
+  open func insert(views _views: [UIView], at index: Int, animated: Bool) {
+
+    var _views = _views
+    _views.removeAll(where: views.contains(_:))
+    views.insert(contentsOf: _views, at: index)
+    _views.forEach { view in
+      register(Cell.self, forCellWithReuseIdentifier: identifier(view))
+    }
+    let batchUpdates: () -> Void = {
+      self.performBatchUpdates({
+        self.insertItems(at: (index ..< index.advanced(by: _views.count)).map({ IndexPath(item: $0, section: 0) }))
+      }, completion: nil)
+    }
+    if animated {
+      UIView.animate(
+        withDuration: 0.5,
+        delay: 0,
+        usingSpringWithDamping: 1,
+        initialSpringVelocity: 0,
+        options: [
+          .beginFromCurrentState,
+          .allowUserInteraction,
+          .overrideInheritedCurve,
+          .overrideInheritedOptions,
+          .overrideInheritedDuration
+        ],
+        animations: batchUpdates,
+        completion: nil)
+
+    } else {
+      UIView.performWithoutAnimation(batchUpdates)
+    }
+  }
+
+  open func insert(views _views: [UIView], before view: UIView, animated: Bool) {
+
+    guard let index = views.firstIndex(of: view) else {
+      return
+    }
+    insert(views: _views, at: index, animated: animated)
+  }
+
+  open func insert(views _views: [UIView], after view: UIView, animated: Bool) {
+
+    guard let index = views.firstIndex(of: view)?.advanced(by: 1) else {
+      return
+    }
+    insert(views: _views, at: index, animated: animated)
+  }
 
   open func remove(view: UIView, animated: Bool) {