Question

我在下面具有以下功能，并且无法摆脱编译警告。警告='withUnsafeBytes'已过时：改为使用withUnsafeBytes<R>(_: (UnsafeRawBufferPointer) throws -> R) rethrows -> R

我尝试了有关withUnsafeBytes（包括stackoverflow.com）的在线文档，但是withUnsafeBytes（）的糟糕文档与异常函数outputStream.write（需要UnsafePointer）混合在一起使我无法理解必须如何传递指针，也无法理解$ 0指的是什么。我知道$ 0是代码闭包的隐式参数，但是我得到的代码没有明确列出闭包参数，因此我无法弄清楚什么是$ 0。

func sendMessage(message: String)
{
    // URL Encode the message
    let URLEncodedMem = UnsafeMutablePointer<UInt8>.allocate(capacity: message.utf8CString.count * 3 + 1)
    defer { URLEncodedMem.deallocate() }
    urlEncode( URLEncodedMem, message )
    let urlEncodedMsg = String( cString: URLEncodedMem )

    // Build the server message to send
    let strToSend = "GET /userInput.mtml?userInput=\(urlEncodedMsg) HTTP/1.1\r\n"
            +       "Host: \(hostName):\(hostPort)\r\n\r\n"
    let data = strToSend.data(using: .utf8)!

    _ = data.withUnsafeBytes { outputStream.write($0, maxLength: data.count) }  // Warning = 'withUnsafeBytes' is deprecated: use `withUnsafeBytes<R>(_: (UnsafeRawBufferPointer) throws -> R) rethrows -> R` instead
}   //  sendMessage

即使SWIFT使用withUnsafeBytes进行其他更改，我也希望代码能够继续工作。

我怀疑问题可能在于不支持withUsafeBytes>？不确定？

Answer 1

这将在Swift 5中正确编译。

let strToSend = "GET /userInput.mtml?userInput=\(urlEncodedMsg) HTTP/1.1\r\n"
    +       "Host: \(hostName):\(hostPort)\r\n\r\n"
let data = strToSend.data(using: .utf8)!

_ = data.withUnsafeBytes { outputStream.write($0.bindMemory(to: UInt8.self).baseAddress!, maxLength: data.count) }

（您可以在SO中找到有关弃用旧withUnsafeBytes的文章。）

但是在您的情况下，您可以简单地将其写为：

let strToSend = "GET /userInput.mtml?userInput=\(urlEncodedMsg) HTTP/1.1\r\n"
    +       "Host: \(hostName):\(hostPort)\r\n\r\n"

outputStream.write(strToSend, maxLength: strToSend.utf8.count)

如何在Swift 5.0中使用withUnsafeBytes（）和outputStream.write（）摆脱警告

1 个答案: