一个简单的 Swift 流读取协议，名为 StreamReader，具有两个具体的实现：GenericStreamReader 和 DataReader。
GenericStreamReader 可以从任何 GenericReadStream 读取数据，而 FileDescriptor（来自 SystemPackage）、FileHandle 和 IntputStream 类已被设置为符合该协议。
let data = ...
let reader = DataReader(data: data)
let readData = try reader.readDataToEnd()
assert(readData == data)
let inputStream = ...
let reader = InputStreamReader(stream: inputStream, bufferSize: 1024, bufferSizeIncrement: 512)
/* Read the stream until a newline (whether macOS or Classic MacOS) is found, and returns the data without the newline. */
let (line, separator) = try reader.readData(upTo: [Data("\n".utf8), Data("\r".utf8)], matchingMode: .anyMatchWins, failIfNotFound: false, includeDelimiter: false)
_ = try reader.readData(size: separator.count) /* We must read the line separator before next read, probably :) */
注意：在上面的示例中，如果文件具有 Windows 换行符，这将在每行之后添加一个空的新行（Windows 的分隔符为 \r\n）。
流读取器还具有一个专用的方法来读取流中的一行
/* Does not return the line separator, _but_ set stream position after the line separator. */
let lineData = try reader.readLine(allowUnixNewLines: true, allowLegacyMacOSNewLines: true, allowWindowsNewLines: true).line