Context

在SWIFT中，我正在try 调用libxlsxwriter C库的一个特定函数.文档在这里:https://libxlsxwriter.github.io/worksheet_8h.html#a62bf44845ce9dcc505bf228999db5afa

该函数组合一个"富字符串"(相当于AttributedString，其中不同的格式/样式适用于不同的范围)，并将其写入Excel工作表中的特定单元格.在C中，该函数的工作方式如下:

lxw_format *bold = workbook_add_format(workbook);
format_set_bold(bold);
 
lxw_format *italic = workbook_add_format(workbook);
format_set_italic(italic);
 
lxw_rich_string_tuple fragment11 = {.format = NULL,   .string = "This is "     };
lxw_rich_string_tuple fragment12 = {.format = bold,   .string = "bold"         };
lxw_rich_string_tuple fragment13 = {.format = NULL,   .string = " and this is "};
lxw_rich_string_tuple fragment14 = {.format = italic, .string = "italic"       };
 
lxw_rich_string_tuple *rich_string1[] = {&fragment11, &fragment12,
                                         &fragment13, &fragment14, NULL};
 
worksheet_write_rich_string(worksheet, CELL("A1"), rich_string1, NULL);

The Problem

我有一个由lxw_rich_string_tuple个 struct 组成的数组，但我不清楚如何将其转换为worksheet_write_rich_string()接受的指针数组:

// The worksheet object and `lxw_format` objects are already existent. 
// This array contains multiple well-formed `lxw_rich_string_tuple` structs, which I can see in the debugger.
//
var rawTuples: [lxw_rich_string_tuple] =  ...


// Parameters: 
//    - the worksheet on which to write this string
//    - the row of the cell in which to write
//    - the column of the cell in which to write
//    - a null-terminated array of pointers to `lxw_rich_string_tuple` structs
//    - an optional format object to use, null in this case.
//
worksheet_write_rich_string(worksheet, 0, 1, ?, NULL);

问题在于?美元.我试过了所有的withUnsafeBytes、withUnsafeMutableBytes和UnsafeMutableRawPointer().bindMemory(to:capacity:)，但我想不出Swift 的胡言乱语怎么能在C中做这么简单的事情.谢谢.

My Attempt

这不会产生编译器错误，但会崩溃，并出现错误访问异常:

let argsSize: Int = rawTuples.count

rawTuples.withUnsafeMutableBufferPointer { rawTuplesPointer in

    let ptr = UnsafeMutableRawPointer(rawTuplesPointer.baseAddress!).bindMemory(to: lxw_rich_string_tuple.self, capacity: argsSize)
    var tuplePointers: [UnsafeMutablePointer<lxw_rich_string_tuple>?] = []

    for i in 0 ..< argsSize
    {
        let tp: UnsafeMutablePointer<lxw_rich_string_tuple>? = ptr + (i * MemoryLayout<lxw_rich_string_tuple>.stride)           
        tuplePointers.append(tp)
    }
    tuplePointers.append(nil)

    tuplePointers.withUnsafeBufferPointer { tpPointer in

        let m = UnsafeMutablePointer(mutating: tpPointer.baseAddress)
        worksheet_write_rich_string(lxw_worksheet, cell.row, cell.col, m, nil)

    }
}