[C#] 文字列を改行コードで1行ずつに分割する方法

string text = GetSampleText();

foreach (var line in text.AsSpan().EnumerateLines())
{
    // line が ReadOnlySpan<char> なので、string にしたければ ToString() で変換
    Console.WriteLine(line.ToString());
}

public static string[] SplitLines(ReadOnlySpan<char> span)
{
    using var builder = new ValueArrayBuilder<string>();

    foreach (var element in span.EnumerateLines())
    {
        builder.Add(element.ToString());
    }

    return builder.ToArray();
}

private static readonly string[] NewLineStrings = ["\r\n", "\n"];

public static string[] SplitLines(string value)
{
    return text.Split(NewLineStrings, StringSplitOptions.None);
}