FileStream

FileStream is a stream for interfacing with files on the filesystem. It is a convenient wrapper over IOStream to automatically set up a file descriptor.

Initialization

The designated initializer for FileStream:

init(path: String, mode: FileMode = .OpenOrCreate, access: FileAccess = .ReadWrite, creationFlags: FileFlags = FileFlags(rawValue: 0o644)) throws

creationFlags is only used for the .CreateNew, .Create, and .OpenOrCreate file modes.

The FileMode enumeration is used to specify how the operating system should open a file.

• .Append
  • Opens the file if it exists and seeks to the end of the file, or creates a new file.
  • Only compatible with .Read access mode
• .Create
  • Specifies that the operating system should create a new file. If the file already exists, it will be overwritten. .Create is equivalent to requesting that if the file does not exist, use .CreateNew; otherwise, use .Truncate.
  • Requires .Write or .ReadWrite access mode
• .CreateNew
  • Specifies that the operating system should create a new file.
  • If the file already exists, an FileStreamError.FileExists is thrown.
• .Open
  • Specifies that the operating system should open an existing file.
• .OpenOrCreate
  • Specifies that the operating system should open a file if it exists; otherwise, a new file should be created.
• .Truncate
  • Specifies that the operating system should open an existing file. When the file is opened, it should be truncated so that its size is zero bytes.
  • Requires the .Write or .ReadWrite access mode

Examples

// open a file, create it if it doesn't exist, and write to it
do {
    var fstream = try FileStream(path: "/Users/eswick/Desktop/testfile")
} catch let e as FileStreamError.FileNotFound {
    print("File not found!")
} catch {
    print("An error occurred while opening the file.")
}
try fstream.write("Hello, world!")

// create a new file, truncating it if it already exists
var flags = FileFlags(rawValue: 0o775)
var fstream = try FileStream(path: "/Users/eswick/Desktop/newfile", mode: .Create, creationFlags: flags)
// ...

// open device and read from it
var urandom = try FileStream(path: "/dev/urandom", mode: .Open)
print(try urandom.read(15))