SwiftUI 日期格式

Question

我從 Github 得到這個： https://github.com/emilioschepis/techfeed當我啟動應用程序時，我在控制台中遇到問題：無法將“Wed，2011 年 8 月 3 日 09:44:00 +0200”轉換為日期. 我有一個黑屏。

我正在使用最新的 xCode 版本並更新代碼。 感謝您的回答....屏幕截圖

解析器：

import Foundation

class ReleasesParser: NSObject {
typealias CompletionResult = ([Release]) -> Void

private static var formatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateFormat = "E, dd MMM yyyy HH:mm:ss z"
    return formatter
}()

private var releases = [Release]()
private var currentElement = ""
private var currentGuid = ""
private var currentTitle = ""
private var currentDescription = ""
private var currentPubDate = ""
private var completion: CompletionResult?

func parse(data: Data, completion: @escaping CompletionResult) {
    self.completion = completion
    
    if data.isEmpty {
        completion([])
        return
    }
    
    let parser = XMLParser(data: data)
    parser.delegate = self
    parser.parse()
}
}

extension ReleasesParser: XMLParserDelegate {
func parserDidStartDocument(_ parser: XMLParser) {
    releases.removeAll(keepingCapacity: true)
}

func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
    currentElement = elementName
    
    // If we are about to start a new item clear the fields
    if currentElement == "item" {
        currentGuid = ""
        currentTitle = ""
        currentDescription = ""
        currentPubDate = ""
    }
}

func parser(_ parser: XMLParser, foundCharacters string: String) {
    switch currentElement {
    case "guid":
        currentGuid += string.trimmingCharacters(in: .whitespacesAndNewlines)
    case "title":
        currentTitle += string.trimmingCharacters(in: .whitespacesAndNewlines)
    case "description":
        currentDescription += string.trimmingCharacters(in: .whitespacesAndNewlines)
    case "pubDate":
        currentPubDate += string.trimmingCharacters(in: .whitespacesAndNewlines)
    default:
        break
    }
}

func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
    // If we are about to end an item add it to the list
    if elementName == "item" {
        guard let date = Self.formatter.date(from: currentPubDate) else {
            print("Could not convert \"\(currentPubDate)\" to Date.")
            return
        }
        
        let release = Release(id: currentGuid,
                                  title: currentTitle,
                                  description: currentDescription,
                                  date: date)
        
        releases.append(release)
    }
}

func parserDidEndDocument(_ parser: XMLParser) {
    completion?(releases)
}}

列表視圖行：

import SwiftUI


struct ReleaseRow : View {
var release: Release

private var formatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateFormat = "E, dd MMM yyyy"
    return formatter
}()

init(_ release: Release) {
    self.release = release
}

var body: some View {
    VStack(alignment: .leading) {
        Text(release.title)
            .font(.headline)
        Text("\(release.date, formatter: formatter)")
            .font(.subheadline)
            .foregroundColor(.gray)
    }
    .frame(height: 44.0)
}}

Answer 1

您在 ListViewRow 中的 dateFormat 為E, dd MMM yyyy ，而您的日期格式為E, dd MMM yyyy HH:mm:ss z 。 您必須使用此 dateFormat 轉換您的日期。

let formatter = DateFormatter()
formatter.dateFormat = "E, dd MMM yyyy HH:mm:ss z"
var date = formatter.date(from: "Wed, 03 Aug 2011 09:44:00 +0200")

然后，您可以使用日期 object 來獲取所需格式的字符串。

Answer 2

有一種更簡單的方法來顯示日期/時間

• iOS 15（ formatted修飾符）
• iOS 14（ formatter參數）

請參見下面的示例：

struct TestFormat: View {
    let releaseDate = Date()
    
    static let stackDateFormat: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "E, dd MMM yyyy HH:mm:ss z"
        return formatter
    }()
    
    var body: some View {
        VStack {
           //iOS 15
         Text(releaseDate.formatted(.dateTime.year().month().day().weekday().hour().minute().second().timeZone()))
            
           //iOS 14 and latter
         Text("\(releaseDate, formatter: Self.stackDateFormat)")
        }
    }
}