獲取UnsafePointer <UInt8> 將Int寫入流中

Question

如何獲得指向數字變量的指針？ 例如，轉換將獲得一個UnsafePointer<UInt8> ，它指向包含Swift Int的存儲。 我需要將Int寫入流中。

我的例子：

public static func writeToOutputStream(text: String!, outputStream:NSOutputStream!){
    let encodedDataArray = [UInt8](text.utf8)
    //send length of the data so the server knows when the message ends.
    outputStream.write(encodedDataArray.count, maxLength: 4)
    outputStream.write(encodedDataArray, maxLength: encodedDataArray.count)
}

如果我也想發送數據長度，我需要encodedDataArray.count是UnsafePointer<UInt8> 。

Answer 1

與withUnsafePointer使用，如下所示：

let outputStream = NSOutputStream(toMemory: ())
outputStream.open()

var count: Int = 0x01020304 // = encodedDataArray.count in your program
withUnsafePointer(&count) { (pointer: UnsafePointer<Int>) -> Void in
    outputStream.write(UnsafePointer<UInt8>(pointer), maxLength: 4)
}

outputStream.propertyForKey(NSStreamDataWrittenToMemoryStreamKey)

結果：

<04030201>

請注意，它將以低字節序寫入字節（因為當前運行Swift的所有平台都是低字節序）。 如果要使用big-endian編寫，請使用encodedDataArray.count.bigEndian 。