mirror of
https://github.com/Instagram/IGListKit
synced 2026-04-29 09:27:17 +00:00
f6e088acd8
Summary: Adding a working range example to the example app. This example: - Displays a list of images downloaded from unsplash.it - Create 20 uniquely-random sized objects - When section controllers enter the range, create a data task to download the image - When finished, store image in `downloadedImage` - Set in cell if cell is visible - Don't create task if already downloaded or task created - Cancel task when section controller is destroyed - Show a spinner cell while downloading the image Fixes #84 - [x] All tests pass. Demo project builds and runs. - [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/CONTRIBUTING.md) Closes https://github.com/Instagram/IGListKit/pull/89 Differential Revision: D4050210 Pulled By: rnystrom fbshipit-source-id: 628a777fa819dccd9d9f4f58646cdf72fb4bc65c
96 lines
3.3 KiB
Swift
96 lines
3.3 KiB
Swift
/**
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Copyright (c) 2016-present, Facebook, Inc. All rights reserved.
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The examples provided by Facebook are for non-commercial testing and evaluation
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purposes only. Facebook reserves all rights not expressly granted.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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import UIKit
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import IGListKit
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class WorkingRangeSectionController: IGListSectionController, IGListSectionType, IGListWorkingRangeDelegate {
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var height: Int?
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var downloadedImage: UIImage?
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var task: URLSessionDataTask?
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var urlString: String? {
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guard let height = height,
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let width = collectionContext?.containerSize.width
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else { return nil }
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return "https://unsplash.it/" + width.description + "/" + height.description
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}
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deinit {
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task?.cancel()
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}
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override init() {
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super.init()
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workingRangeDelegate = self
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}
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func numberOfItems() -> Int {
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return 2
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}
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func sizeForItem(at index: Int) -> CGSize {
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let width: CGFloat = collectionContext?.containerSize.width ?? 0
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let height: CGFloat = CGFloat(index == 0 ? 55 : (self.height ?? 0))
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return CGSize(width: width, height: height)
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}
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func cellForItem(at index: Int) -> UICollectionViewCell {
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let cellClass: AnyClass = index == 0 ? LabelCell.self : ImageCell.self
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let cell = collectionContext!.dequeueReusableCell(of: cellClass, for: self, at: index)
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if let cell = cell as? LabelCell {
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cell.label.text = urlString
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} else if let cell = cell as? ImageCell {
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cell.setImage(image: downloadedImage)
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}
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return cell
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}
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func didUpdate(to object: Any) {
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self.height = object as? Int
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}
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func didSelectItem(at index: Int) {}
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//MARK: IGListWorkingRangeDelegate
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func listAdapter(_ listAdapter: IGListAdapter, sectionControllerWillEnterWorkingRange sectionController: IGListSectionController) {
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guard downloadedImage == nil,
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task == nil,
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let urlString = urlString,
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let url = URL(string: urlString)
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else { return }
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let section = collectionContext?.section(for: self) ?? 0
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print("Downloading image \(urlString) for section \(section)")
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task = URLSession.shared.dataTask(with: url, completionHandler: { data, response, err in
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if let data = data, let image = UIImage(data: data) {
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DispatchQueue.main.async {
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self.downloadedImage = image
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if let cell = self.collectionContext?.cellForItem(at: 1, sectionController: self) as? ImageCell {
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cell.setImage(image: image)
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}
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}
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} else {
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print("Error downloading \(urlString): \(err)")
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}
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})
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task?.resume()
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}
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func listAdapter(_ listAdapter: IGListAdapter, sectionControllerDidExitWorkingRange sectionController: IGListSectionController) {}
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}
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