Ios swift:collectionView单元格中的标签
在我的collectionView中,我有7个部分和3个单元 单击单元格时下载文件的我的代码:Ios swift:collectionView单元格中的标签,ios,swift,uicollectionview,Ios,Swift,Uicollectionview,在我的collectionView中,我有7个部分和3个单元 单击单元格时下载文件的我的代码: enum DownloadStatus { case none case inProgress case completed case failed } struct item { var title : String! var downloadStatus : DownloadStatus = .none init(title: String
enum DownloadStatus {
case none
case inProgress
case completed
case failed
}
struct item {
var title : String!
var downloadStatus : DownloadStatus = .none
init(title: String) {
self.title = title
}
}
var downloadQ = [Int: [Int]]()
typealias ProgressHandler = (Int, Float) -> ()
var items = [[item]]()
var tableId = 0
var onProgress : ProgressHandler?
override func viewDidLoad() {
super.viewDidLoad()
items = [
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")],
[item(title: "item 2"),item(title: "item 2"),item(title: "item 2")]
]
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return media.count
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return media[section].count
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
var item = self.items[indexPath.section][indexPath.row]
downloadQ[indexPath.section]?.append(indexPath.row)
var theArray = downloadQ[indexPath.section] ?? [Int]()
theArray.append(indexPath.row)
downloadQ[indexPath.section] = theArray
// Create the actions
let url = URL(string: "link")!
let downloadManager = DownloadManager()
downloadManager.identifier = indexPath.row
downloadManager.tableId = indexPath.section
downloadManager.folderPath = "folder"
let downloadTaskLocal = downloadManager.activate().downloadTask(with: url)
downloadTaskLocal.resume()
var cell = self.collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! MasterViewCell
cell = self.collectionView?.cellForItem(at: indexPath) as! MasterViewCell
cell.label?.isHidden = false
downloadManager.onProgress = { (row, tableId, progress) in
DispatchQueue.main.async {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
if appDelegate.masterVC == nil {
return
}
if appDelegate.masterVC.tableId != tableId {
return
}
let indexpath = IndexPath.init(row: row, section: indexPath.section)
var cell = self.collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! MasterViewCell
cell = appDelegate.masterVC.collectionView.cellForItem(at: indexpath) as! MasterViewCell
cell.label?.text = "\(CGFloat(progress))%"
}
}
}
我的下载管理器类:
import Foundation
import UIKit
extension URLSession {
func getSessionDescription () -> Int {
// row id
return Int(self.sessionDescription!)!
}
func getDebugDescription () -> Int {
// table id
return Int(self.debugDescription)!
}
}
class DownloadManager : NSObject, URLSessionDelegate, URLSessionDownloadDelegate {
static var shared = DownloadManager()
var identifier : Int = -1
var tableId : Int = -1
var folderPath : String = ""
typealias ProgressHandler = (Int, Int, Float) -> ()
var onProgress : ProgressHandler? {
didSet {
if onProgress != nil {
let _ = activate()
}
}
}
override init() {
super.init()
}
func activate() -> URLSession {
let config = URLSessionConfiguration.background(withIdentifier: "\(Bundle.main.bundleIdentifier!).background.\(NSUUID.init())")
let urlSession = URLSession(configuration: config, delegate: self, delegateQueue: OperationQueue())
urlSession.sessionDescription = String(identifier)
urlSession.accessibilityHint = String(tableId)
return urlSession
}
private func calculateProgress(session : URLSession, completionHandler : @escaping (Int, Int, Float) -> ()) {
session.getTasksWithCompletionHandler { (tasks, uploads, downloads) in
let progress = downloads.map({ (task) -> Float in
if task.countOfBytesExpectedToReceive > 0 {
return Float(task.countOfBytesReceived) / Float(task.countOfBytesExpectedToReceive)
} else {
return 0.0
}
})
//print("tbale id \(session.accessibilityHint ?? "hit")")
let stringNumb = (session.accessibilityHint ?? "hit")
let someNumb = Int(stringNumb as String) // 1357 as integer
let string1 = (session.sessionDescription ?? "hit")
let some1 = Int(string1 as String) // 1357 as integer
if let idx = downloadQ[someNumb!]?.index(of: some1!) {
downloadQ[someNumb!]?.remove(at: idx)
//print("remove:\(downloadQ)")
}
completionHandler(session.getSessionDescription(), Int(session.accessibilityHint!)!, progress.reduce(0.0, +))
}
}
func urlSession(_ session: URLSession,
downloadTask: URLSessionDownloadTask,
didFinishDownloadingTo location: URL){
let stringNumb = (session.accessibilityHint ?? "hit")
let someNumb = Int(stringNumb as String) // 1357 as integer
let string1 = (session.sessionDescription ?? "hit")
let some1 = Int(string1 as String) // 1357 as integer
if let idx = downloadQ[someNumb!]?.index(of: some1!) {
downloadQ[someNumb!]?.remove(at: idx)
//print("remove:\(downloadQ)")
}
let fileName = downloadTask.originalRequest?.url?.lastPathComponent
let path = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
let documentDirectoryPath:String = path[0]
let fileManager = FileManager()
var destinationURLForFile = URL(fileURLWithPath: documentDirectoryPath.appending("/\(folderPath)"))
do {
try fileManager.createDirectory(at: destinationURLForFile, withIntermediateDirectories: true, attributes: nil)
destinationURLForFile.appendPathComponent(String(describing: fileName!))
try fileManager.moveItem(at: location, to: destinationURLForFile)
}catch(let error){
print(error)
}
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
let stringNumb = (session.accessibilityHint ?? "hit")
let someNumb = Int(stringNumb as String) // 1357 as integer
let string1 = (session.sessionDescription ?? "hit")
let some1 = Int(string1 as String) // 1357 as integer
if let idx = downloadQ[someNumb!]?.index(of: some1!) {
downloadQ[someNumb!]?.remove(at: idx)
//print("remove:\(downloadQ)")
}
if totalBytesExpectedToWrite > 0 {
if let onProgress = onProgress {
calculateProgress(session: session, completionHandler: onProgress)
}
let progress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite)
//debugPrint("Progress \(downloadTask) \(progress)")
}
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
let stringNumb = (session.accessibilityHint ?? "hit")
let someNumb = Int(stringNumb as String) // 1357 as integer
let string1 = (session.sessionDescription ?? "hit")
let some1 = Int(string1 as String) // 1357 as integer
if let idx = downloadQ[someNumb!]?.index(of: some1!) {
downloadQ[someNumb!]?.remove(at: idx)
//print("remove:\(downloadQ)")
}
//debugPrint("Task completed: \(task), error: \(String(describing: error))")
}
}
但我有个问题。我的应用程序在此行崩溃-cell=self.collectionView?.cellForItem(at:indexPath)as!主视图单元
出现此问题:致命错误:在展开可选值时意外发现nil。如何修复它?您面临的问题是由于单元重用。每次在集合或表格中滚动时,通常会取消旧单元格的显示。这意味着,无论何时显示新单元格
cellForRow
(表格)或itemForRow
(集合),都必须有数据才能为单元格提供数据
如果只将有关下载过程的数据存储到计算单元中,则在调用prepareforuse:
,system call时会丢失这些数据,因为计算单元被重置
另一种方法是使用静态单元格。因为静态单元格永远不会重置。但是,只有当你在屏幕上使用少量项目时,这才方便。如果您有数十个或数百个单元,那么性能将非常昂贵。您必须保存进度值,而不是仅保存downloadTaskLocal。您应该为每次下载创建一个下载对象,并保存到阵列中。每个下载对象将负责下载一个任务。在下载对象中保留所有下载信息。例如进度等,以便在创建单元格时访问此数组以设置值。@vivekDas I更新问题。并在更新标题下添加新代码。如何修复它?永远不要在
cellForItemAt
之外调用dequeueReusableCell
。它不能工作。与cellForItemAt
不同,您无法将单元格返回框架。请使用like->as?@vadian抱歉。我不知道如何解决问题。你能告诉我更多的情况吗?也许你可以举个例子?