准备Swift 4 - UnsafeMutablePointer迁移到UnsafeMutableBufferPointer

Question

我有一个char-by-char函数，它返回一个文件中的字符。就我而言，这是非常高效的。

Xcode表示将在Swift 4.0中删除characterPointer.initialize(from: s.characters)＆＃34;＆＃34;我必须＆＃34;使用＆＃39; UnsafeMutableBufferPointer.initialize（来自：）＆＃39;代替＆＃34;

但我无法得到它。你能解释一下吗？如何使用带有UnsafeMutableBufferPointer的字符快速迭代器？你有一个例子吗？

这是我的功能：

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

    if atEof {
        return nil
    }

    if stored_cnt > (stored_idx + 1) {
        stored_idx += 1
        let char = characterPointer.pointee
        characterPointer = characterPointer.successor()
        return char
    }

    let tmpData = fileHandle.readData(ofLength: (chunkSize))
    if tmpData.count == 0 {
        atEof = true
        return nil
    }

    if var s = NSString(data: tmpData, encoding: encoding.rawValue) as String! {
        characterPointer.initialize(from: s.characters)

        stored_idx = 0
        stored_cnt = s.characters.count
    }
    let char = characterPointer.pointee
    characterPointer = characterPointer.successor()
    return char
}

顺便说一下，如果有更快的解决方案，请不要犹豫告诉我。

非常感谢。