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//
// ViewController.swift
// Sample
//
// Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
import UIKit
import AsyncDisplayKit
final class ViewController: ASViewController, ASTableDataSource, ASTableDelegate {
struct State {
var itemCount: Int
var fetchingMore: Bool
static let empty = State(itemCount: 20, fetchingMore: false)
}
enum Action {
case BeginBatchFetch
case EndBatchFetch(resultCount: Int)
}
var tableNode: ASTableNode {
return node as! ASTableNode
}
private(set) var state: State = .empty
init() {
super.init(node: ASTableNode())
tableNode.delegate = self
tableNode.dataSource = self
}
required init?(coder aDecoder: NSCoder) {
fatalError("storyboards are incompatible with truth and beauty")
}
// MARK: ASTableNode data source and delegate.
func tableNode(tableNode: ASTableNode, nodeForRowAtIndexPath indexPath: NSIndexPath) -> ASCellNode {
// Should read the row count directly from table view but
// https://github.com/facebook/AsyncDisplayKit/issues/1159
let rowCount = self.tableNode(tableNode, numberOfRowsInSection: 0)
if state.fetchingMore && indexPath.row == rowCount - 1 {
let node = TailLoadingCellNode()
node.style.height = ASDimensionMake(44.0)
return node;
}
let node = ASTextCellNode()
node.text = String(format: "[%ld.%ld] says hello!", indexPath.section, indexPath.row)
return node
}
func numberOfSectionsInTableNode(tableNode: ASTableNode) -> Int {
return 1
}
func tableNode(tableNode: ASTableNode, numberOfRowsInSection section: Int) -> Int {
var count = state.itemCount
if state.fetchingMore {
count += 1
}
return count
}
func tableNode(tableNode: ASTableNode, willBeginBatchFetchWithContext context: ASBatchContext) {
/// This call will come in on a background thread. Switch to main
/// to add our spinner, then fire off our fetch.
dispatch_async(dispatch_get_main_queue()) {
let oldState = self.state
self.state = ViewController.handleAction(.BeginBatchFetch, fromState: oldState)
self.renderDiff(oldState)
}
ViewController.fetchDataWithCompletion { resultCount in
let action = Action.EndBatchFetch(resultCount: resultCount)
let oldState = self.state
self.state = ViewController.handleAction(action, fromState: oldState)
self.renderDiff(oldState)
context.completeBatchFetching(true)
}
}
private func renderDiff(oldState: State) {
self.tableNode.performBatchUpdates({
// Add or remove items
let rowCountChange = state.itemCount - oldState.itemCount
if rowCountChange > 0 {
let indexPaths = (oldState.itemCount..<state.itemCount).map { index in
NSIndexPath(forRow: index, inSection: 0)
}
tableNode.insertRowsAtIndexPaths(indexPaths, withRowAnimation: .None)
} else if rowCountChange < 0 {
assertionFailure("Deleting rows is not implemented. YAGNI.")
}
// Add or remove spinner.
if state.fetchingMore != oldState.fetchingMore {
if state.fetchingMore {
// Add spinner.
let spinnerIndexPath = NSIndexPath(forRow: state.itemCount, inSection: 0)
tableNode.insertRowsAtIndexPaths([ spinnerIndexPath ], withRowAnimation: .None)
} else {
// Remove spinner.
let spinnerIndexPath = NSIndexPath(forRow: oldState.itemCount, inSection: 0)
tableNode.deleteRowsAtIndexPaths([ spinnerIndexPath ], withRowAnimation: .None)
}
}
}, completion:nil)
}
/// (Pretend) fetches some new items and calls the
/// completion handler on the main thread.
private static func fetchDataWithCompletion(completion: (Int) -> Void) {
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(NSTimeInterval(NSEC_PER_SEC) * 1.0))
dispatch_after(time, dispatch_get_main_queue()) {
let resultCount = Int(arc4random_uniform(20))
completion(resultCount)
}
}
private static func handleAction(action: Action, fromState state: State) -> State {
var state = state
switch action {
case .BeginBatchFetch:
state.fetchingMore = true
case let .EndBatchFetch(resultCount):
state.itemCount += resultCount
state.fetchingMore = false
}
return state
}
}