FileDescriptor

public struct FileDescriptor

The FileDescriptor struct is used to perform low-level file operations.

Example: Open and read a ASCII file

import SwiftIO

// Open the file located in "/subDir/hello.txt"
let file = FileDescriptor.open("/SD:/subDir/hello.txt")

//Initialize a buffer to store the reading bytes.
var buffer = UnsafeMutableRawBufferPointer.allocate(byteCount: 10, alignment: 4)

// Read bytes into the buffer
file.read(into: buffer)

// Print the reding bytes.
for i in 0..<buffer.count {
    print(buffer[i])
}

while true {
    sleep(ms: 1000)
}

  • Options for specifying what a file descriptor’s offset is relative to.

    See more

    Declaration

    Swift

    public enum SeekOrigin : Int32

  • Open or creates, if does not exist, file.

    Attention

    The root directory for the micro SD card is “/SD:/”

    Declaration

    Swift

    public static func open(_ path: String) -> FileDescriptor

    Parameters

    path

    REQUIRED The location of the file to open.

  • Deletes the specified file or directory

    Declaration

    Swift

    public static func unlink(_ path: String)

    Parameters

    path

    REQUIRED The location of the file to open.

  • Flushes the associated stream and closes the file.

    Declaration

    Swift

    public func close()

  • Get current file position.

    Declaration

    Swift

    public func tell() -> Int

    Return Value

    Current position in file.

  • Reads bytes at the current file offset into a buffer

    Declaration

    Swift

    public func read(into buffer: UnsafeMutableRawBufferPointer) -> Int

    Parameters

    buffer

    REQUIRED Te region of memory to read into.

  • Reads bytes at the specified offset into a buffer.

    Declaration

    Swift

    public func read(fromAbsoluteOffest offset: Int, into buffer: UnsafeMutableRawBufferPointer) -> Int

    Parameters

    offset

    REQUIRED The file offset where reading begins.
    buffer

    REQUIRED Te region of memory to read into.

  • Reposition the offset for the given file descriptor.

    Declaration

    Swift

    public func seek(offset: Int, from whence: SeekOrigin = .start) -> Int

    Parameters

    offset

    REQUIRED The new offset for the file descriptor.
    whence

    OPTIONAL The origin of the new offset.

  • Writes the contents of a buffer at the current file offset.

    Declaration

    Swift

    public func write(_ buffer: UnsafeRawBufferPointer)

    Parameters

    buffer

    REQUIRED The region of memory that contains the data being written.

  • Writes the contents of a string at the current file offset.

    Declaration

    Swift

    public func write(_ string: String)

    Parameters

    string

    REQUIRED The string being written.

  • Writes the contents of a buffer at the specified offset.

    Declaration

    Swift

    public func write(toAbsoluteOffset offset: Int, _ buffer: UnsafeRawBufferPointer)

    Parameters

    offset

    REQUIRED The file offset where writing begins.
    buffer

    REQUIRED Te region of memory that contains the data being written.

  • Flushes any cached write of an open file.

    Attention

    This method can be used to flush the cache of an open file. This can be called to ensure data gets written to the storage media immediately. This may be done to avoid data loss if power is removed unexpectedly. Note that closing a file will cause caches to be flushed correctly so it need not be called if the file is being closed.

    Declaration

    Swift

    public func sync()