无法解码Swift 5中的base64字符串

if let base64String = "your_base64_string_here",
   let decodedData = Data(base64Encoded: base64String) {
    // 使用解码后的数据，例如转换为字符串
    if let decodedString = String(data: decodedData, encoding: .utf8) {
        print("解码后的字符串: \(decodedString)")
    }
} else {
    print("Base64字符串无效或解码失败")
}

extension String {
    func base64Decoded() -> String? {
        guard let data = Data(base64Encoded: self) else { return nil }
        return String(data: data, encoding: .utf8)
    }
}

// 使用扩展方法
if let decodedString = "your_base64_string_here".base64Decoded() {
    print("解码后的字符串: \(decodedString)")
} else {
    print("Base64字符串无效或解码失败")
}

let base64URLString = "your_url_safe_base64_string_here"
let base64StandardString = base64URLString.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")

if let decodedData = Data(base64Encoded: base64StandardString),
   let decodedString = String(data: decodedData, encoding: .utf8) {
    print("解码后的字符串: \(decodedString)")
} else {
    print("Base64字符串无效或解码失败")
}

func addPadding(to base64: String) -> String {
    var base = base64
    while base.count % 4 != 0 {
        base.append("=")
    }
    return base
}

let base64String = "your_base64_string_here"
let paddedBase64 = addPadding(to: base64String)

if let decodedData = Data(base64Encoded: paddedBase64),
   let decodedString = String(data: decodedData, encoding: .utf8) {
    print("解码后的字符串: \(decodedString)")
} else {
    print("Base64字符串无效或解码失败")
}

import Foundation

func decodeBase64String(_ base64String: String) -> String? {
    // 处理URL安全字符
    var standardBase64 = base64String.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
    
    // 添加填充
    while standardBase64.count % 4 != 0 {
        standardBase64.append("=")
    }
    
    // 解码
    guard let data = Data(base64Encoded: standardBase64) else {
        print("无效的Base64字符串")
        return nil
    }
    
    // 转换为字符串
    return String(data: data, encoding: .utf8)
}

let base64Str = "your_base64_string_here"
if let decodedStr = decodeBase64String(base64Str) {
    print("解码成功: \(decodedStr)")
} else {
    print("解码失败")
}