speaktoalvin · May 24, 2016 09:55 · May 18, 2016
diff --git a/CollectionViewBinder.swift b/CollectionViewBinder.swift
@@ -0,0 +1,240 @@
+import UIKit
+import Foundation
+import ReactiveCocoa
+import Result
+import Dwifft
+
+/**
+ Encapsulates information about collection view nib/cell registration.
+
+ - Nib:   UINib.
+ - Class: UICollectionViewCell class.
+ */
+private enum RegisteredType {
+    case Nib(UINib)
+    case Class(AnyClass)
+}
+
+/// CollectionViewBinder is a ReactiveCocoa helper class for simplifying using `UICollectionView`s with ReactiveCocoa.
+/// Using the binder lets the view configuration for collection view cells move to the view and out of the view controller.
+final class CollectionViewBinder<T: Equatable>: NSObject, UICollectionViewDataSource, UICollectionViewDelegate {
+
+        /// `UICollectionViewDelegate` object.
+    weak var delegate: UICollectionViewDelegate? {
+        get { return self.collectionView?.delegate }
+        set { self.collectionView?.delegate = newValue }
+    }
+
+        /// `CollectionBinderDataSource` object.
+    weak var dataSource: CollectionBinderDataSource? {
+        willSet {
+            if let _ = newValue {
+                reloadData()
+            }
+        }
+    }
+
+        /// `UICollectionView` associated with the binder.
+    private(set) weak var collectionView: UICollectionView?
+
+        /// Signal that emits the data
+    private var dataSignal: SignalProducer<[[T]], NoError>
+        /// Signal that emits the supplementary data
+    private var supplementarySignal: SignalProducer<[String: [T]], NoError>?
+
+        /// Mutable data property
+    private let data = MutableProperty<[[T]]>([])
+        /// Mutable supplementary data property
+    private let supplementaryData: MutableProperty<[String: [T]]> = MutableProperty<[String: [T]]>([:])
+
+
+    // MARK: - Registration Information
+
+        /// All the cells registered with the binder.
+    private var cells: [String: RegisteredType] = [:]
+        /// All the supplementary views registered with the binder.
+    private var supplementaries: [String: (String, RegisteredType)] = [:]
+        /// All the decoration views registered with the binder.z
+    private var decorations: [String: RegisteredType] = [:]
+
+    /**
+     Create a binding helper.
+
+     - parameter collectionView:      Collection view object to bind data to.
+     - parameter dataSignal:          SignalProducer that emits changes to the underlying data.
+     - parameter supplementarySignal: SignalProducer that emits changes to the data the represents headers, footers, etc.
+     */
+    init(collectionView: UICollectionView, dataSignal: SignalProducer<[[T]], NoError>, supplementarySignal: SignalProducer<[String: [T]], NoError>?) {
+        self.collectionView = collectionView
+        self.dataSignal = dataSignal
+        self.supplementarySignal = supplementarySignal
+
+        super.init()
+        self.data <~ self.dataSignal
+        self.supplementaryData <~ self.supplementarySignal ?? SignalProducer.empty
+        self.collectionView?.dataSource = self
+
+        self.data.producer.on(next: { print($0.count) }).on(next: { _ in self.reloadData() }).takeUntil(self.willDeallocSignal()).start()
+    } 
+
+    // MARK: - UICollectionViewDataSource
+
+    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
+        guard let _ = self.dataSource where !self.cells.isEmpty else {
+            return 0
+        }
+        return self.data.value.count
+    }
+
+
+    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
+        guard let _ = self.dataSource where !self.cells.isEmpty && section < self.data.value.count else {
+            return 0
+        }
+        return self.data.value[section].count
+    }
+
+    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
+        guard let dataSource = self.dataSource else {
+            return UICollectionViewCell()
+        }
+        let model = self.data.value[indexPath.section][indexPath.item]
+        if let reuseIdentifier = dataSource.collectionView(collectionView, reuseIdentifierForItemAtIndexPath: indexPath) {
+            let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath)
+            if cell is ReactiveView {
+                (cell as! ReactiveView).bindViewModel(model)
+            }
+            return cell
+        }
+        return UICollectionViewCell()
+    }
+
+    func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
+
+        if let model = self.supplementaryData.value[kind]?[indexPath.section],
+            reuseIdentifier = self.dataSource?.collectionView(collectionView, reuseIdentifierForSupplementaryViewOfKind: kind, atIndexPath: indexPath) {
+            let view = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: reuseIdentifier, forIndexPath: indexPath)
+            if view is ReactiveView {
+                (view as! ReactiveView).bindViewModel(model)
+            }
+            return view
+        }
+        return UICollectionReusableView()
+    }
+}
+
+// MARK: - Registering Views
+extension CollectionViewBinder {
+
+    /**
+     Register a nib for a cell reuse identifier.
+
+     - parameter nib:        Nib object.
+     - parameter identifier: Reuse identifier to register the specified nib with.
+     */
+    func registerNib(nib: UINib, forCellReuseIdentifier identifier: String) {
+        self.cells[identifier] = .Nib(nib)
+        self.collectionView?.registerNib(nib, forCellWithReuseIdentifier: identifier)
+    }
+
+    /**
+     Register a class for a cell reuse identifier.
+
+     - parameter aClass:     Class object.
+     - parameter identifier: Reuse identifier to register the specified class with.
+     */
+    func registerClass(aClass: AnyClass, forCellReuseIdentifier identifier: String) {
+        self.cells[identifier] = .Class(aClass)
+        self.collectionView?.registerClass(aClass, forCellWithReuseIdentifier: identifier)
+    }
+
+    /**
+     Register a nib for a supplementary reuse identifier.
+
+     - parameter nib:        Nib object.
+     - parameter kind:       Supplementary element kind.
+     - parameter identifier: Reuse identifier to register the specified nib with.
+     */
+    func registerNib(nib: UINib, forSupplementaryViewOfKind kind: String, withReuseIdentifier identifier: String) {
+        self.supplementaries[kind] = (identifier, .Nib(nib))
+        self.collectionView?.registerNib(nib, forSupplementaryViewOfKind: kind, withReuseIdentifier: identifier)
+    }
+
+    /**
+     Register a class for a supplementary reuse identifier.
+
+     - parameter aClass:     Class object.
+     - parameter kind:       Supplementary element kind.
+     - parameter identifier: Reuse identifier to register the specified class with.
+     */
+    func registerClass(aClass: AnyClass, forSupplementaryViewOfKind kind: String, withReuseIdentifier identifier: String) {
+        self.supplementaries[kind] = (identifier, .Class(aClass))
+        self.collectionView?.registerClass(aClass, forSupplementaryViewOfKind: kind, withReuseIdentifier: identifier)
+    }
+
+    /**
+     Register a nib for a decoration kind.
+
+     - parameter nib:         Nib object.
+     - parameter elementKind: Decoration identifier.
+     */
+    func registerNib(nib: UINib, forDecorationViewOfKind elementKind: String) {
+        self.decorations[elementKind] = .Nib(nib)
+        self.collectionView?.collectionViewLayout.registerNib(nib, forDecorationViewOfKind: elementKind)
+    }
+
+    /**
+     Register a class for a decoration kind.
+
+     - parameter aClass:      Class object.
+     - parameter elementKind: Decoration identifier.
+     */
+    func registerClass(aClass: AnyClass, forDecorationViewOfKind elementKind: String) {
+        self.decorations[elementKind] = .Class(aClass)
+        self.collectionView?.collectionViewLayout.registerClass(aClass, forDecorationViewOfKind: elementKind)
+    }
+
+}
+
+// MARK: - Reloading
+extension CollectionViewBinder {
+    /**
+     Reload the binder.
+     */
+    func reloadData() {
+        dispatch_async(dispatch_get_main_queue(), { [weak self] in
+            self?.collectionView?.reloadData()
+        })
+    }
+
+    /**
+     Reload the specified sections.
+
+     - parameter indexes: Index set of sections to reload.
+     */
+    func reloadSections(indexes: NSIndexSet) {
+        dispatch_async(dispatch_get_main_queue(), { [weak self] in
+            self?.collectionView?.reloadSections(indexes)
+        })
+    }
+
+    /**
+     Reload all the items at the specified index paths.
+
+     - parameter indexPaths: List of index paths to reload.
+     */
+    func reloadItemsAtIndexPaths(indexPaths: [NSIndexPath]) {
+        dispatch_async(dispatch_get_main_queue(), { [weak self] in
+            self?.collectionView?.reloadItemsAtIndexPaths(indexPaths)
+        })
+    }
+
+    /**
+     Reload the input views.
+     */
+    func reloadInputViews() {
+        dispatch_async(dispatch_get_main_queue(), { [weak self] in
+            self?.collectionView?.reloadInputViews()
+        })
+    }
+}
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