为 NSStream 快速创建字节缓冲区持有者

Question

在 Ray Wenderlich tutorial on sockets 中，为了从 Objective-C 中的输入流中读取字节，我们做了

uint8_t buffer[1024];
        int len;

        while ([inputStream hasBytesAvailable]) {
            len = [inputStream read:buffer maxLength:sizeof(buffer)];
            if (len > 0) {

                NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

                if (nil != output) {
                    NSLog(@"server said: %@", output);
                }

在 Swift 中，我尝试了以下方法，但没有成功

        if (stream == inputStream) {
//            var buffer = Array<UInt8>(count: 1024, repeatedValue: 0)
            var buffer : UnsafeMutablePointer<UInt8>
            var len : Bool

            while (inputStream?.hasBytesAvailable == true) {
                len = inputStream?.getBuffer(buffer, length: sizeofValue(buffer))

                if (len) {
                    var output = String(NSString(bytes: buffer, length: sizeofValue(buffer), encoding: NSASCIIStringEncoding))

                }
            }
        }

Answer 1

您可以使用Array<UInt8> 作为缓冲区并按原样传递documented in Using Swift with Cocoa and Objective-C：

let bufferSize = 1024
var buffer = Array<UInt8>(count: bufferSize, repeatedValue: 0)

let bytesRead = inputStream.read(&buffer, maxLength: bufferSize)
if bytesRead >= 0 {
    var output = NSString(bytes: &buffer, length: bytesRead, encoding: NSUTF8StringEncoding)
} else {
    // Handle error
}

-[NSInputStream read:maxLength:] 返回一个数字，表示它读取了多少字节（如果它 >= 0）或是否有错误（如果它是负数）。您应该相应地检查返回值。