【发布时间】：2020-07-28 19:09:47
【问题描述】：
我有一个应用程序，用户可以在其中搜索待售商品。我目前正在尝试添加功能，以便用户可以查看按价格从低到高排序的项目。在用户点击排序按钮后，他们会看到另一个显示不同排序选项的视图控制器。第一个是“价格：从低到高”。在从低到高被点击后，我使用协议发回一个函数并委托给当前的 ResultsTableViewController 。一切正常，直到我尝试根据价格进行排序。当我print(data) 我回来了
[app.UserPostData(id: Optional("61E93673-24B8-42BE-B0AA-7185A0F26A39"), userSub: Optional("e345fdac-7eb5-4cde-a421-aa758b05d999"), fileName: Optional("823AD3EF-2890-40C4-A1F2-47FCDDA5A64B"),userPostedImage: Optional(<UIImage:0x600002e9b330 anonymous {1239, 1241}>), description: Optional("example description"), dateUploaded: Optional("2020-07-28")), app.UserPostData(id: Optional("9373925E-5526-4D92-B104-7981CD226669"), userSub: Optional("e345fdac-7eb5-4cde-a421-aa758b05d999"), fileName: Optional("0703758F-60AE-4566-A0A0-0EF16C1711BE"), price: Optional(50000),userPostedImage: Optional(<UIImage:0x600002e9fb10 anonymous {1238, 1240}>), description: Optional("example description"), dateUploaded: Optional("2020-07-28")), app.UserPostData(id: Optional("0FC678A6-B308-4A05-8B36-093768375A79"), userSub: Optional("e345fdac-7eb5-4cde-a421-aa758b05d999"), fileName: Optional("555ADDD0-5E58-4577-A2FD-52B6F47AC747"), price: Optional(650), userPostedImage: Optional(<UIImage:0x600002e80240 anonymous {1238, 1240}>), description: Optional("example description"), dateUploaded: Optional("2020-07-27"))]
如何将数组排序/重新排列为价格从低到高显示的项目？在我的排序函数中，我收到一条错误消息 Binary operator '>' cannot be applied to two 'Int?' operands 。
struct UserPostData {
var id: String?
var userSub: String?
var fileName: String?
var price: Int?
var userPostedImage: UIImage?
var description: String?
var dateUploaded: String?
}
class ResultsTableViewController: UITableViewController, priceLowToHigh, priceHightoLow {
func sortPriceLowToHigh(sort: String) {
print(sort)
print(data)
data.sort(by: { $0.price > $1.price}) // This is where I get the error
}
func sortPriceHighToLow(sort: String) {
print(sort)
}
var data: [UserPostData] = []
var userSubID = String()
let activityIndicator = UIActivityIndicatorView()
override func viewDidLoad() {
super.viewDidLoad()
setView()
getData()
}
override func numberOfSections(in tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return data.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCell(withIdentifier: "Results") as! CellResults
cell.image = data[indexPath.section].userPostedImage
cell.price = data[indexPath.section].price
cell.layoutSubviews()
self.tableView.rowHeight = UITableView.automaticDimension
return cell
}
func setView(){
let sortButton = UIBarButtonItem(title: "Sort", style: .plain, target: self, action: #selector(sortPressed))
navigationItem.rightBarButtonItem = sortButton
}
func getData(){
activityIndicator.hidesWhenStopped = true
activityIndicator.translatesAutoresizingMaskIntoConstraints = false
activityIndicator.style = .large
activityIndicator.startAnimating()
tableView.addSubview(activityIndicator)
NSLayoutConstraint.activate([activityIndicator.centerXAnchor.constraint(equalTo: tableView.safeAreaLayoutGuide.centerXAnchor),
activityIndicator.centerYAnchor.constraint(equalTo: tableView.safeAreaLayoutGuide.centerYAnchor)])
userSubID = AWSMobileClient.default().userSub!
let post = Post.keys
let predicate = post.search == search
_ = Amplify.API.query(request: .list(SellerPost.self, where: predicate)) { event in
switch event {
case .success(let result):
switch result {
case .success(let posts):
DispatchQueue.main.async {
self.tableView.reloadData()
for element in posts{
_ = Amplify.Storage.downloadData(key: element.filename,progressListener: { progress in
print("Progress: \(progress)")},
resultListener: { (event) in
switch event {
case let .success(data):
DispatchQueue.main.async {
self.data.append(UserPostData.init(id: element.id, userSub: element.userSub, fileName: element.filename, price: element.price, userPostedImage: UIImage(data: data), description: element.description,dateUploaded: element.dateUploaded))
self.tableView.reloadData()
self.activityIndicator.stopAnimating()
}
print("Completed: \(data)")
case let .failure(storageError):
print("Failed: \(storageError.errorDescription). \(storageError.recoverySuggestion)")
}
})
}
}
case .failure(let error):
print("Got failed result with \(error.errorDescription)")
}
case .failure(let error):
print("Got failed event with error \(error)")
}
}
self.tableView.register(CellResults.self, forCellReuseIdentifier: "Results")
}
@objc func sortPressed(){
print("sort clicked")
let sTVC = SortViewController()
sTVC.priceLowToHighDelegate = self
sTVC.priceHighToLowDelegate = self
sTVC.modalPresentationStyle = .custom
self.present(sTVC, animated: true, completion: nil)
}
}
【问题讨论】：
标签： swift