Question

在以前版本的swift中，我能够使用这篇帖子的答案： Read a file/URL line-by-line in Swift

在swift中逐行读取文件。现在我已升级到1.2，这似乎不再编译。是否有更新的方法在swift 1.2中逐行读取文件？

Answer 1

以下是Swift 1.2的StreamReader的更新版本（如果有人想查看它以确保它没问题，那么现在应该将其编辑成原始答案，因为1.2是当前的发布版本）：

class StreamReader  {

    let encoding : UInt
    let chunkSize : Int

    var fileHandle : NSFileHandle!
    let buffer : NSMutableData!
    let delimData : NSData!
    var atEof : Bool = false

    init?(path: String, delimiter: String = "\n", encoding : UInt = NSUTF8StringEncoding, chunkSize : Int = 4096) {
        self.chunkSize = chunkSize
        self.encoding = encoding

        if let fileHandle = NSFileHandle(forReadingAtPath: path),
               delimData = delimiter.dataUsingEncoding(NSUTF8StringEncoding),
               buffer = NSMutableData(capacity: chunkSize)
        {
            self.fileHandle = fileHandle
            self.delimData = delimData
            self.buffer = buffer
        } else {
            self.fileHandle = nil
            self.delimData = nil
            self.buffer = nil
            return nil
        }
    }

    deinit {
        self.close()
    }

    /// Return next line, or nil on EOF.
    func nextLine() -> String? {
        precondition(fileHandle != nil, "Attempt to read from closed file")

        if atEof {
            return nil
        }

        // Read data chunks from file until a line delimiter is found:
        var range = buffer.rangeOfData(delimData, options: nil, range: NSMakeRange(0, buffer.length))
        while range.location == NSNotFound {
            var tmpData = fileHandle.readDataOfLength(chunkSize)
            if tmpData.length == 0 {
                // EOF or read error.
                atEof = true
                if buffer.length > 0 {
                    // Buffer contains last line in file (not terminated by delimiter).
                    let line = NSString(data: buffer, encoding: encoding)

                    buffer.length = 0
                    return line as String?
                }
                // No more lines.
                return nil
            }
            buffer.appendData(tmpData)
            range = buffer.rangeOfData(delimData, options: nil, range: NSMakeRange(0, buffer.length))
        }

        // Convert complete line (excluding the delimiter) to a string:
        let line = NSString(data: buffer.subdataWithRange(NSMakeRange(0, range.location)),
            encoding: encoding)
        // Remove line (and the delimiter) from the buffer:
        buffer.replaceBytesInRange(NSMakeRange(0, range.location + range.length), withBytes: nil, length: 0)

        return line as String?
    }

    /// Start reading from the beginning of file.
    func rewind() -> Void {
        fileHandle.seekToFileOffset(0)
        buffer.length = 0
        atEof = false
    }

    /// Close the underlying file. No reading must be done after calling this method.
    func close() -> Void {
        fileHandle?.closeFile()
        fileHandle = nil
    }
}

Answer 2

Apple正在收紧语言的语法，因此在Swift 1.2版中不再允许以前版本中允许的内容。您将不得不通过并清理代码以便编译。

在swift 1.2中逐行读取文件

2 个答案: