我正在尝试使用XML文件中的条目填充表格视图。到目前为止，我已经将XML文件解析为Struct并编写了titleForHeaderInSection和numberOfSections的方法，但是我正在努力通过计算每个<holiday>中的<calendarevent>项来计算每个节的numberOfRows。我认为我的主要努力来自于不了解如何使用[section]。到目前为止，这是我所做的：
我已经解析了一个具有日历日期和事件的xml文件。您将看到第一个日历事件如何具有2个假日和描述条目，而第二个事件如何具有1.：
<calendar>
<calendarevent>
<month>October</month>
<dateevent>2018 10 01</dateevent>
<datenumber>01</datenumber>
<holiday>First Holiday</holiday>
<description>aaaaaaaaaa</description>
<holiday>Second Holiday</holiday>
<description>bbbbbbbbbb</description>
</calendarevent>
<calendarevent>
<month>October</month>
<dateevent>2018 10 10</dateevent>
<datenumber>10</datenumber>
<holiday>Third Holiday</holiday>
<description>ccccccccccc</description>
</calendarevent>
.... and so on
对于这样的结构：
struct CalendarDates {
struct CalendarEvents {
var month = ""
var eventdate = ""
var eventdatenumber = ""
var holiday = ""
var description = ""
}
}
这是我的XML解析器代码：
class CalendarViewController {
var myCalendarDatesFromStrut = [CalendarDates]()
var myCalendarEventsFromStrut = [CalendarDates.CalendarEvents]()
}
extension CalendarViewController {
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
calendarEventsElementFromXML = elementName
}
func parser(_ parser: XMLParser, foundCharacters string: String) {
let data = string.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
if data.count != 0 {
switch calendarEventsElementFromXML
{
case "month": monthsFromXML = data
case "dateevent": eventdatesFromXML = data
case "datenumber": eventdatenumbersFromXML = data
case "holiday": holidaysFromXML = data
default: break
}
}
}
func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
if elementName == "calendarevent" {
var myCalendarDates = CalendarDates.CalendarEvents()
myCalendarDates.month = monthsFromXML
myCalendarDates.eventdate = eventdatesFromXML
myCalendarDates.eventdatenumber = eventdatenumbersFromXML
myCalendarDates.holiday = holidaysFromXML
myCalendarEventsFromStrut.append(myCalendarDates)
}
}
}
因此，在解析XML并将其附加到结构之后，我开始获取tableview的值。
如果<calendarevent>与当前日期月份相同，则每个部分都由一个<month>组成。 XML具有其他月份的<calendarevent>，所以我不希望所有这些。我检查当前月份是否为XML中的==月，如果是，则将numberofSections计数为numberOfSections，并将dateevents格式化为这些部分的标题。
然后，节中的每一行代表相应的<holiday>中的一个<calendarevent>。
extension CalendarViewController: UITableViewDelegate, UITableViewDataSource {
//Calculates # of <dateevents> in current month
func numberOfSections(in tableView: UITableView) -> Int {
formatter.dateFormat = "MMMM"
let currentMonthShown = formatter.string(from: selectedDate)
let allEventsInVisibleMonth = myCalendarEventsFromStrut.filter({ $0.month == currentMonthShown }).map {$0.eventdate}.count
return allEventsInVisibleMonth
}
// Prints <dateevent> reformatted as section header
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
formatter.dateFormat = "MMMM"
let currentMonthShown = formatter.string(from: selectedDate)
let allEventsInVisibleMonth = myCalendarEventsFromStrut.filter({ $0.month == currentMonthShown }).map {$0.eventdate}
formatter.dateFormat = "yyyy-MM-dd"
let eventStringsToDate = allEventsInVisibleMonth.map{ formatter.date(from: $0) }
formatter.dateFormat = "yyyy-MM-dd"
formatter.dateStyle = .long
formatter.timeStyle = .none
let eventDatesBackToString = eventStringsToDate.map{ formatter.string(from: $0 as! Date )}
return eventDatesBackToString[section]
}
现在，节中的每一行都需要在相应的<holiday>中代表一个<calendarevent>-这就是我遇到的问题。
对于表视图的numberOfRowsInSection，我需要计算每个<holiday>中的<calendarevent>个条目中的＃个，并在每个节中显示＃行。然后在cellForRowAt中打印。有人可以给我提示这里的逻辑吗？
这是我尝试过的方法，也是我失败的地方：
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
formatter.dateFormat = "MMMM"
let currentMonthShown = formatter.string(from: selectedDate)
let allEventsInMonth = myCalendarEventsFromStrut.filter({ $0.month == currentMonthShown }).map {$0.holiday}
return allEventsInMonth.count //This gets me same number of rows in all sections = total # of events in current month.
//I'm struggling to figure out how to get # of events at a particular section, so I can make that the # of rows
}
答案 0 :(得分：1)
首先，XML可能在单个holiday中包含多个calendarevent元素，因此您需要更新CalendarEvents才能容纳多个假期。
struct Holiday {
var title: String = ""
var description: String = ""
}
//You should better avoid plural form for something which represents a single object
struct CalendarEvent {
var month: String = ""
var eventdate: String = ""
var eventdatenumber: String = ""
//Better use plural form for the name representing multiple objects
var holidays: [Holiday] = []
}
（我删除了外部结构CalendarDates，因为找不到任何需要嵌套类型的原因。此外，我建议您避免使用复数形式来命名代表单个对象的东西。）
要使用结构解析XML，您需要在XMLParserDelegate中使用更多属性：
class CalendarViewController: UIViewController {
//`myCalendarEventsFromStrut` is too long and `FromStrut` does not make sense
var myCalendarEvents: [CalendarEvent] = []
//Properties needed for parsing your XML
var textCurrentlyParsed: String? = nil
var monthFromXML: String = ""
var dateeventFromXML: String = ""
var datenumberFromXML: String = ""
var holidaysFromXML: [Holiday] = []
//Your table view shows some selected evnets in `myCalendarEvents`,
//To improve response, you should beter keep the filtered result, when `selectedDate` is updated.
var selectedDate: Date? {
didSet {
if let date = selectedDate {
let currentMonthShown = monthFormatter.string(from: date)
allEventsInVisibleMonth = myCalendarEvents.filter({ $0.month == currentMonthShown })
} else {
allEventsInVisibleMonth = [] //Or you prefer `allEventsInVisibleMonth = myCalendarEvents`?
}
}
}
var allEventsInVisibleMonth: [CalendarEvent] = []
//You may have this sort of constants somewhere, this is just an example
let TheCellID = "cell" //Change this according to your actual setups
//
// Date formatters.
// Better keep distinct DateFormaters accoding to the format to avoid simple mistakes
//
let monthFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "MMMM"
return formatter
}()
let dateeventFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy MM dd"
return formatter
}()
let sectionHeaderFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy-MM-dd"
return formatter
}()
//...
}
（上面的代码进行了一些补充，以编写UITableViewDataSource方法的示例。）
使用上面的属性，您可以编写XMLParserDelegate方法，如下所示：
extension CalendarViewController: XMLParserDelegate {
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
switch elementName {
case "month", "dateevent", "datenumber", "holiday", "description":
//Reset the text content for the element
textCurrentlyParsed = ""
case "calendarevent":
//Reset all variables which may contain the result of previous element
monthFromXML = ""
dateeventFromXML = ""
datenumberFromXML = ""
holidaysFromXML = []
case "calendar":
//Can be ignored
break
default:
print("Unexpected start tag:", elementName)
break
}
}
func parser(_ parser: XMLParser, foundCharacters string: String) {
//`parser(_:foundCharacters:)` may be called several times for a seemingly single text content,
//So you need to add the `string` to the currently parsed text
textCurrentlyParsed? += string
}
func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
switch elementName {
case "calendarevent":
var calendarEvent = CalendarEvent()
calendarEvent.month = monthFromXML
calendarEvent.eventdate = dateeventFromXML
calendarEvent.eventdatenumber = datenumberFromXML
calendarEvent.holidays = holidaysFromXML
myCalendarEvents.append(calendarEvent)
case "month":
if let parsedText = textCurrentlyParsed?.trimmingCharacters(in: .whitespacesAndNewlines) {
monthFromXML = parsedText
}
case "dateevent":
if let parsedText = textCurrentlyParsed?.trimmingCharacters(in: .whitespacesAndNewlines) {
dateeventFromXML = parsedText
}
case "datenumber":
if let parsedText = textCurrentlyParsed?.trimmingCharacters(in: .whitespacesAndNewlines) {
datenumberFromXML = parsedText
}
case "holiday":
if let parsedText = textCurrentlyParsed?.trimmingCharacters(in: .whitespacesAndNewlines) {
var holiday = Holiday()
holiday.title = parsedText
holidaysFromXML.append(holiday)
}
break
case "description":
if
let parsedText = textCurrentlyParsed?.trimmingCharacters(in: .whitespacesAndNewlines),
case let lastIndexOfHoliday = holidaysFromXML.count - 1, lastIndexOfHoliday >= 0
{
//You need to modify the last entry in `holidaysFromXML`
holidaysFromXML[lastIndexOfHoliday].description = parsedText
}
default:
print("Unexpected end tag:", elementName)
break
}
}
}
（如果您不需要trim这些文本，可以将上面的代码简化一些。）
包含这些代码后，您的UITableViewDataSource方法将如下所示：
extension CalendarViewController: UITableViewDelegate, UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
return allEventsInVisibleMonth.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return allEventsInVisibleMonth[section].holidays.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let eventForTheSection = allEventsInVisibleMonth[indexPath.section]
let holidayForTheRow = eventForTheSection.holidays[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: TheCellID, for: indexPath)
//... setup the cell using `eventForTheSection` and `holidayForTheRow`
return cell
}
// Prints <dateevent> reformatted as section header
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
let eventForTheSection = allEventsInVisibleMonth[section]
if let eventdateAsDate = dateeventFormatter.date(from: eventForTheSection.eventdate) {
return sectionHeaderFormatter.string(from: eventdateAsDate)
} else {
return "Broken eventdate: \(eventForTheSection.eventdate)"
}
}
}
（未经测试，您可能需要一些修复。）
通常，UITableViewDataSource方法可以经常调用，因此您应该有效地实现它们。
因此，不建议在每次调用时创建一个过滤数组。
您最好仅在以下情况下更新allEventsInVisibleMonth：
myCalendarEvents已更新（上面的代码中未包含）selectedDate已更新（didSet中的selectedDate会做到）有点长，但是我认为值得尝试。