swift - 当表格中的行数超过 7 时,多个表格视图单元格的背景颜色会发生变化
问题描述
我正在从 Firebase 读取数据,然后在 tableview 单元格中显示这些数据。还有一个存储在本地的文件,其中包含每个单元格的已读/未读状态。该文件包含 Firebase 中每个孩子的密钥,我将其与每个单元格中的数据相匹配。
基本上,如果单元格具有在文件中也找到的键,则该数据被用户视为“已读取”。但是,如果单元格具有在本地文件中没有等效项的密钥,则此数据被视为“未读”。
到目前为止,这完美无缺。然后我为每个单元格添加了两个滑动功能。先标记为已读,也标记为未读。当标记为“已读”时,滑动会调用一个函数,该函数将单元格的密钥写入本地文件。相反,当标记为“未读”时,滑动会调用另一个从本地文件中删除密钥的函数。这也很完美。
但是,在滑动时,我还必须更改单元格背景颜色以反映“已读”或“未读”。这会导致问题,因为重新加载单元格以供重用......在我的情况下,我在重新加载之前获得了 7 个单元格。
这意味着如果我有超过 7 个单元格,并且我将某些内容标记为“已读”,我最终会更改多个单元格的背景颜色。文件写入工作正常......只是背景颜色被复制了。
我将 editActionsForRowAt 函数中的颜色更改如下:
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
let Action2 = UITableViewRowAction(style: .default, title: "Mark Read", handler: { (action, indexPath) in
// 函数在设置颜色之前继续做一些事情...
if filteredMessageIDforSwipe.count == 0 {
let selectedCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
selectedCell.contentView.backgroundColor = UIColor(hexString: "#ffffff")
请注意,我没有选择一个单元格......而是滑动,然后尝试更改被滑动单元格的单元格背景颜色。
显然,我只希望我刷过的单元格改变颜色,而不是另一个单元格(如果我有超过 7 个单元格)。
谢谢!
N。
编辑:我已经按照下面的建议修改了 editActionsForRowAt,但没有效果。
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
selectedRowIndexForReadUnread = indexPath.row
let Action2 = UITableViewRowAction(style: .default, title: "Mark Read", handler: { (action, indexPath) in
if filteredMessageIDforSwipe.count == 0 && selectedRowIndexForReadUnread = indexPath.row {
let selectedCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
selectedCell.contentView.backgroundColor = UIColor(hexString: "#ffffff")
编辑:作为参考,这里是 editActionsForRowAt 函数... Action2 和 Action5 是相关的。
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
selectedRowIndexForReadUnread = indexPath.row
if tableView == self.Nomination2SearchTableView {
let Action1 = UITableViewRowAction(style: .default, title: "Select", handler: { (action, indexPath) in
self.Nomination2SearchTableView.isHidden = true
self.Nomination2TableView.isHidden = false
NominationState = "Active"
let SearchObject: Nomination2SearchModel
SearchObject = Nomination2SearchList[indexPath.row]
userIDStringforNominationSearch = SearchObject.UserIDString!
let FullName = SearchObject.Full_Name
self.FullNameLabel.isHidden = false
self.FullNameLabel.text = "Showing " + FullName! + "'s Shout Outs"
self.LoadDataFromNominationafterSearch()
self.ActiveButton.setTitleColor(.orange, for: .normal)
let banner = NotificationBanner(title: "Tip", subtitle: "Swipe to select a user.", style: .info)
banner.haptic = .none
banner.show()
//We are setting the editor mode to the opposite of what is displayed in the tableview, because EditorMode text is what is displayed when you swipe the cell.
// EditorMode = "Set to Complete"
})
return [Action1]
}
if tableView == self.Nomination2TableView{
if NominationState == "Active" {
let Action2 = UITableViewRowAction(style: .default, title: "Mark Read", handler: { (action, indexPath) in
let searchObject9: Nomination2Model
searchObject9 = Nomination2List[indexPath.row]
let messageIDKey = searchObject9.key
let filename = self.getDocumentsDirectory().appendingPathComponent("output.txt")
do {
let textStringFromFile = try String(contentsOf: filename, encoding: .utf8)
var result: [(messageID: String, readStatus: String)] = []
// var indexCount = result.count
let rows = textStringFromFile.components(separatedBy: "\n")
for row in rows {
let columns = row.components(separatedBy: ",")
result.append((columns[0], columns[1]))
}
filteredMessageIDforSwipe = result.filter { $0.messageID == (messageIDKey) }
}
catch{
}
if filteredMessageIDforSwipe.count == 0 {
let selectedCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
// let selectedCellForReadMessages:UITableViewCell = self.Nomination2TableView.cellForRow(at: indexPath)! as! Nomination2TableViewCell
selectedCell.contentView.backgroundColor = UIColor(hexString: "#ffffff")
// let myReadCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
// myReadCell.NominationNameLabel.textColor = UIColor.lightGray
// myReadCell.NominationTextLabel.textColor = UIColor.lightGray
let NominationObject: Nomination2Model
NominationObject = Nomination2List[indexPath.row]
nominationKeyForWhenCellSelected = NominationObject.key
self.writeFile()
// self.removeRowFromFile()
}
if filteredMessageIDforSwipe.count > 0 {
let alert = UIAlertController(title: "Failure",
message: "Shout-out is already read!",
preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default))
self.present(alert, animated: true, completion: nil)
}
})
let Action5 = UITableViewRowAction(style: .default, title: "Mark Unread", handler: { (action, indexPath) in
let searchObject9: Nomination2Model
searchObject9 = Nomination2List[indexPath.row]
let messageIDKey = searchObject9.key
let filename = self.getDocumentsDirectory().appendingPathComponent("output.txt")
do {
let textStringFromFile = try String(contentsOf: filename, encoding: .utf8)
var result: [(messageID: String, readStatus: String)] = []
// var indexCount = result.count
let rows = textStringFromFile.components(separatedBy: "\n")
for row in rows {
let columns = row.components(separatedBy: ",")
result.append((columns[0], columns[1]))
}
filteredMessageIDforSwipe = result.filter { $0.messageID == (messageIDKey) }
}
catch{
}
if filteredMessageIDforSwipe.count > 0 {
let selectedCell:UITableViewCell = tableView.cellForRow(at: indexPath)!
selectedCell.contentView.backgroundColor = UIColor(hexString: "#fcf0e5")
// let myCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
// myCell.NominationNameLabel.textColor = UIColor.orange
// myCell.NominationTextLabel.textColor = UIColor.black
let NominationObject: Nomination2Model
NominationObject = Nomination2List[indexPath.row]
nominationKeyForWhenCellSelected = NominationObject.key
// self.writeFile()
self.removeRowFromFile()
}
if filteredMessageIDforSwipe.count == 0 {
let alert = UIAlertController(title: "Failure",
message: "Shout-out is already unread!",
preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default))
self.present(alert, animated: true, completion: nil)
}
})
Action2.backgroundColor = UIColor.lightGray
Action5.backgroundColor = UIColor.blue
return[Action2, Action5]
}
if NominationState == "Approve"{
let Action3 = UITableViewRowAction(style: .default, title: NominationState, handler: { (action, indexPath) in
let searchObject9: Nomination2Model
searchObject9 = Nomination2List[indexPath.row]
ForName = searchObject9.ForName!
FromName = searchObject9.FromName!
ForWhat = searchObject9.ForWhat!
key = searchObject9.key!
ForUserID = searchObject9.ForUserID!
FromUserID = searchObject9.FromUserID!
PointsGifted = searchObject9.PointsGifted!
NominationText = searchObject9.NominationText!
ImageNameNominations = searchObject9.ImageNameString!
ImageURLNominations = searchObject9.ImageURL!
databaseReference = Database.database().reference()
databaseReference.child("Users").child(FromUserID).observeSingleEvent(of: DataEventType.value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
let CurrentPointsRedeemed = value?["Points_Redeemed"] as? Int
let CurrentPointsBalance = value? ["Points_Balance"] as? Int
let NewPointsRedeemed = CurrentPointsRedeemed! + PointsGifted
let NewPointsBalance = CurrentPointsBalance! - PointsGifted
if NewPointsBalance >= 0{
databaseReference.child("Users").child(FromUserID).updateChildValues(["Points_Redeemed": NewPointsRedeemed])
databaseReference.child("Users").child(FromUserID).updateChildValues(["Points_Balance": NewPointsBalance])
self.postToFirebase()
self.giftPoints()
self.pendingCount()
Nomination2List.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath], with: .fade)
}
if NewPointsBalance <= 0{
let alert = UIAlertController(title: "Nominations",
message: "Not Enough Points for approval",
preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default))
self.present(alert, animated: true, completion: nil)
}
})
})
Action3.backgroundColor = UIColor.blue
return[Action3]
}
//here
//Action2.backgroundColor = UIColor.blue
//return[Action2]
else{
return [UITableViewRowAction]()
}
}
else {
return [UITableViewRowAction]()
}
}
解决方案
表格视图单元格被重用这就是其他单元格的背景颜色发生变化的原因。
有一个很好的关于swift 黑客攻击的代码片段,它完全可以满足您的需要。我也在我自己的项目中使用这个片段。
所以在你的情况下,它看起来像这样:
let backgroundView = UIView()
backgroundView.backgroundColor = UIColor(red:0.94, green:0.94, blue:0.94, alpha:1.0)
cell.selectedBackgroundView = backgroundView
用这个替换你的代码,我认为它会好的。希望这可以帮助。
编辑:
要仅更改滑动单元格的颜色,您可以尝试在 if 语句之后插入 else 语句。你可以试试这个:
let selectedCell = self.Nomination2TableView.cellForRow(at: indexPath) as! Nomination2TableViewCell
if filteredMessageIDforSwipe.count == 0 {
selectedCell.contentView.backgroundColor = UIColor(hexString: "#ffffff")
} else {
selectedCell.contentView.backgroundColor = UIColor.white
//or whatever the color of the background is by default
}
如果这不能解决问题,请告诉我!
编辑2:
我在一个(过于简化的)小测试应用程序中重新创建了您问题的核心。回顾一下,这就是我理解的问题的核心:您想设置在表格视图中滑动的单元格的颜色。您还希望它们在重新打开应用程序时保持该颜色,并防止其他单元格因单元格重复使用而着色。
在下面的解决方案中,我没有使用您使用的完全相同的对象和变量,因为如果没有完整的代码,将很难重新创建。相反,这是您可以在自己的解决方案中实现的逻辑。因此,您似乎保留了选定的单元格 indexPaths filteredMessageIDforSwipe
- 因此您应该遍历该数组并为具有相应索引路径的单元格设置颜色。在调用 for 循环之前设置默认的单元格背景颜色很重要。
这是我的示例视图控制器:
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
@IBOutlet weak var tableView: UITableView!
let userDefaults = UserDefaults.standard
let testArray = ["Test1", "Test2", "Test3", "Test4", "Test5", "Test6", "Test7", "Test8", "Test9", "Test10", "Test11", "Test12", "Test13", "Test14", "Test15", "Test16", "Test17", "Test18", "Test19", "Test20"]
var selectedCellIndexPaths = [Int]()
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
if let values = userDefaults.value(forKey: "IndexPathsArray") as? Array<Int> {
selectedCellIndexPaths = values
}
print("selected", selectedCellIndexPaths)
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return testArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel?.text = testArray[indexPath.row]
cell.backgroundColor = UIColor.white
for indx in selectedCellIndexPaths {
if indexPath.row == indx {
cell.backgroundColor = UIColor.red
}
}
return cell
}
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
let cell = tableView.cellForRow(at: indexPath)
let action = UITableViewRowAction(style: .default, title: "Mark Read") { (action, indexPath) in
cell?.backgroundColor = UIColor.red
self.selectedCellIndexPaths.append(indexPath.row)
self.userDefaults.set(self.selectedCellIndexPaths, forKey: "IndexPathsArray")
print(self.selectedCellIndexPaths)
}
return [action]
}
}
如果您需要进一步的帮助,请告诉我!
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