Swift中的免費橋接和指針訪問

Question

我正在將一個App從Objective-C移植到Swift，我需要使用以下方法：

CFStreamCreatePairWithSocketToHost(alloc: CFAllocator!, host: CFString!, port: UInt32, \
readStream: CMutablePointer<Unmanaged<CFReadStream>?>, \
writeStream: CMutablePointer<Unmanaged<CFWriteStream>?>)

舊的邏輯看起來像這樣（幾個網站似乎都同意）：

CFReadStreamRef readStream = NULL;
CFWriteStreamRef writeStream = NULL;
CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)(host), port, \
                                   &readStream, &writeStream);

NSInputStream inputStream = (__bridge_transfer NSInputStream *)readStream;
NSOutputStream outputStream = (__bridge_transfer NSOutputStream *)writeStream;

由於免費橋接，這很好用。 但是，ARC在“Swift-space”中不存在，並且類型系統已經改變。

如何將我的流變成實例

CMutablePointer<Unmanaged<CFReadStream>?>, and
CMutablePointer<Unmanaged<CFWriteStream>?>

然后在CFStreamCreatePairWithSocketToHost調用之后將它們轉換回NSStream子類？

Answer 1

我得到了它的工作，這是我的代碼：確保你在某處保留連接類的引用:-)

class Connection : NSObject, NSStreamDelegate {
    let serverAddress: CFString = "127.0.0.1"
    let serverPort: UInt32 = 8443

    private var inputStream: NSInputStream!
    private var outputStream: NSOutputStream!

    func connect() {
        println("connecting...")

        var readStream:  Unmanaged<CFReadStream>?
        var writeStream: Unmanaged<CFWriteStream>?

        CFStreamCreatePairWithSocketToHost(nil, self.serverAddress, self.serverPort, &readStream, &writeStream)

        // Documentation suggests readStream and writeStream can be assumed to
        // be non-nil. If you believe otherwise, you can test if either is nil
        // and implement whatever error-handling you wish.

        self.inputStream = readStream!.takeRetainedValue()
        self.outputStream = writeStream!.takeRetainedValue()

        self.inputStream.delegate = self
        self.outputStream.delegate = self

        self.inputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
        self.outputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

        self.inputStream.open()
        self.outputStream.open()
    }

    func stream(stream: NSStream, handleEvent eventCode: NSStreamEvent) {
        println("stream event")
    }
}

Answer 2

我無法得到其他人在此主題中提供的示例。 當然，他們編譯了，但是一旦連接打開就會崩潰。

但是，我在WWDC 2014討論（和iOS 8發行說明）中注意到，有一種新方法可以初始化NSStream以創建一對綁定的輸入/輸出流。

見下文：

var inputStream: NSInputStream?
var outputStream: NSOutputStream?

NSStream.getStreamsToHostWithName("localhost", port: 1234, inputStream: &inputStream, outputStream: &outputStream)

這消除了對笨拙的CFStreamCreatePairWithSocketToHost調用的需要，並消除了對非托管資源的需求。

Answer 3

我找到了如何做到這一點。 一些重要的注意事項：

1. 如果使用＆運算符，將自動創建CMutablePointers 。
2. 你可以在得到T在Unmanaged<T>與.getUnretainedValue()和getRetainedValue()似乎.getUnretainedValue()是類似於__bridge_transfer ）
3. Optionals自動初始化為nil 。
4. 如果可選項為nil ，則會轉換為false條件。

到目前為止，我（未經測試）：

var readStream: Unmanaged<CFReadStream>?
var writeStream: Unmanaged<CFWriteStream>?

CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host, port, \
&readStream, &writeStream)

if (readStream && writeStream) {
    inputStream = readStream!.takeUnretainedValue();
    outputStream = writeStream!.takeUnretainedValue();
}

Answer 4

我正在使用NSStream類的getStreamsToHostWithName函數。 它比CFStreamCreatePairWithSocketToHost更容易和更容易

func initNetworkCommunication（）{

print("connecting...")

let serverAddress = "gzoa.vps.infomaniak.com"
let serverPort = 1234

NSStream.getStreamsToHostWithName(serverAddress, port: serverPort, inputStream: &inputStream, outputStream: &outputStream)

self.inputStream!.delegate = self
self.outputStream!.delegate = self

self.inputStream!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
self.outputStream!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

self.inputStream!.open()
self.outputStream!.open()

}

Answer 5

Swift 3版本的CF和NS代碼。 兩者都適合我。

CF：

class Connection: NSObject, StreamDelegate {

private var inputStream: InputStream!
private var outputStream: OutputStream!

var connected = false

func connect(host: String, port: UInt32) {
    var readStream:  Unmanaged<CFReadStream>?
    var writeStream: Unmanaged<CFWriteStream>?

    CFStreamCreatePairWithSocketToHost(nil, host as CFString, port, &readStream, &writeStream)

    self.inputStream = readStream!.takeRetainedValue()
    self.outputStream = writeStream!.takeRetainedValue()

    if let inputStream = inputStream, let outputStream = outputStream {
        inputStream.delegate = self
        outputStream.delegate = self

        inputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
        outputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)

        inputStream.open()
        outputStream.open()

        connected = true
    }
}

func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
    print("stream event, \(eventCode)")
}

}

NS：

class NSConnection: NSObject, StreamDelegate {

private var inputStream: InputStream?
private var outputStream: OutputStream?

var connected = false

func connect(host: String, port: Int) {
    Stream.getStreamsToHost(withName: host, port: port, inputStream: &inputStream, outputStream: &outputStream)

    if let inputStream = inputStream, let outputStream = outputStream {
        inputStream.delegate = self
        outputStream.delegate = self

        inputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
        outputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)

        inputStream.open()
        outputStream.open()
    }
}

func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
    print("stream event, \(eventCode)")
}

}