CFStream Reference

Framework	CoreFoundation/CoreFoundation.h
Declared in	CFFTPStream.h CFHTTPStream.h CFHost.h CFNetServices.h CFSocketStream.h CFStream.h
Companion guides	Getting Started with Networking, Internet, and Web CFNetwork Programming Guide

Overview

This document describes the generic CFStream functions, data types, and constants. See also CFReadStreamRef and CFWriteStreamRef for functions and constants specific to read and write streams respectively.

Functions

CFStreamCreateBoundPair

Creates a pair of read and write streams.

void CFStreamCreateBoundPair (
   CFAllocatorRef alloc,
   CFReadStreamRef *readStream,
   CFWriteStreamRef *writeStream,
   CFIndex transferBufferSize
);

Parameters

alloc: The allocator to use to allocate memory for the new objects. Pass NULL or kCFAllocatorDefault to use the current default allocator.
readStream: Upon return, a readable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.
writeStream: Upon return, a writable. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.
transferBufferSize: The size of the buffer to use to transfer data from readStream to writeStream.

Availability

Available in iOS 2.0 and later.

Related Sample Code

SimpleURLConnections

Declared In

CFStream.h

CFStreamCreatePairWithPeerSocketSignature

Creates readable and writable streams connected to a socket.

void CFStreamCreatePairWithPeerSocketSignature (
   CFAllocatorRef alloc,
   const CFSocketSignature *signature,
   CFReadStreamRef *readStream,
   CFWriteStreamRef *writeStream
);

Parameters

alloc: The allocator to use to allocate memory for the new objects. Pass NULL or kCFAllocatorDefault to use the current default allocator.
signature: A CFSocketSignature structure identifying the communication protocol and address to which the socket streams should connect.
readStream: On return, a readable stream connected to the socket address in signature. If you pass NULL, this function will not create a readable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.
writeStream: On return, a writable stream connected to the socket address in signature. If you pass NULL, this function will not create a writable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.

Discussion

The streams do not open a connection to the socket until one of the streams is opened.

Most properties are shared by both streams. Setting the property for one stream automatically sets the property for the other.

Availability

Available in iOS 2.0 and later.

Declared In

CFStream.h

CFStreamCreatePairWithSocket

Creates readable and writable streams connected to a socket.

void CFStreamCreatePairWithSocket (
   CFAllocatorRef alloc,
   CFSocketNativeHandle sock,
   CFReadStreamRef *readStream,
   CFWriteStreamRef *writeStream
);

Parameters

alloc: The allocator to use to allocate memory for the new objects. Pass NULL or kCFAllocatorDefault to use the current default allocator.
sock: The pre-existing (and already connected) socket which the socket streams should use.
Important: By default, your app is responsible for closing this socket after you close both streams. If you want CFNetwork to take ownership of the socket, set the kCFStreamPropertyShouldCloseNativeSocket property of the stream to kCFBooleanTrue.
readStream: Upon return, a readable stream connected to the socket address in signature. If you pass NULL, this function will not create a readable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.
writeStream: Upon return, a writable stream connected to the socket address in signature. If you pass NULL, this function will not create a writable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.

Discussion

Most properties are shared by both streams. Setting the property for one stream automatically sets the property for the other.

Availability

Available in iOS 2.0 and later.

Related Sample Code

Declared In

CFStream.h

CFStreamCreatePairWithSocketToHost

Creates readable and writable streams connected to a TCP/IP port of a particular host.

void CFStreamCreatePairWithSocketToHost (
   CFAllocatorRef alloc,
   CFStringRef host,
   UInt32 port,
   CFReadStreamRef *readStream,
   CFWriteStreamRef *writeStream
);

Parameters

alloc: The allocator to use to allocate memory for the CFReadStream and CFWriteStream objects. Pass NULL or kCFAllocatorDefault to use the current default allocator.
host: The host name to which the socket streams should connect. The host can be specified using an IPv4 or IPv6 address or a fully qualified DNS host name.
port: The TCP port number to which the socket streams should connect.
readStream: Upon return, a readable stream connected to the socket address in port. If you pass NULL, this function will not create a readable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.
writeStream: Upon return, a writable stream connected to the socket address in port. If you pass NULL, this function will not create a writable stream. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.

Discussion

The streams do not open a connection to the specified host until one of the streams is opened.

Most properties are shared by both streams. Setting the property for one stream automatically sets the property for the other.

Availability

Available in iOS 2.0 and later.

Declared In

CFStream.h

Data Types

CFStreamError

The structure returned by CFReadStreamGetError and CFWriteStreamGetError. (Deprecated. Use CFReadStreamCopyError and CFWriteStreamCopyError instead.)

typedef struct {
   CFStreamErrorDomain domain;
   SInt32 error
} CFStreamError;

Fields

domain: The error domain that should be used to interpret the error. See CFStream Error Domain Constants for possible values.
error: The error code.

Availability

Available in iOS 2.0 and later.

Declared In

CFStream.h

CFStreamClientContext

A structure provided when an application registers itself to receive stream-related events.

struct CFStreamClientContext {
   CFIndex version;
   void *info;
   void *(*retain)(void *info);
   void (*release)(void *info);
   CFStringRef (*copyDescription)(void *info);
} CFStreamClientContext;

Fields

version: An integer of type CFIndex. Currently the only valid value is zero.
info: A pointer to allocated memory containing user-defined data that will be valid for as long as the client is registered with the stream. You may assign NULL if your callback function doesn’t want to receive user-defined data.
retain: A pointer to a function callback that retains the data pointed to by the info field.You may set this function pointer to NULL.
release: A pointer to a function callback that releases the data pointed to by the info field.You may set this function pointer to NULL but doing so might result in memory leaks.
copyDescription: A pointer to a function callback that provides a description of the data pointed to by the info field. In implementing this function, return a reference to a CFString object that describes your allocator, particularly some characteristics of your user-defined data. You may set this function pointer to NULL, in which case Core Foundation will provide a rudimentary description.

Constants

CFStream Status Constants

Constants that describe the status of a stream.

typedef enum {
   kCFStreamStatusNotOpen = 0,
   kCFStreamStatusOpening,
   kCFStreamStatusOpen,
   kCFStreamStatusReading,
   kCFStreamStatusWriting,
   kCFStreamStatusAtEnd,
   kCFStreamStatusClosed,
   kCFStreamStatusError
} CFStreamStatus;

Constants

kCFStreamStatusNotOpen

The stream is not open for reading or writing.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusOpening

The stream is being opened for reading or for writing.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusOpen

The stream is open.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusReading

The stream is being read from.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusWriting

The stream is being written to.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusAtEnd

There is no more data to read, or no more data can be written.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusClosed

The stream is closed.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamStatusError

An error occurred on the stream.

Available in iOS 2.0 and later.

Declared in CFStream.h.

Discussion

The CFStreamStatus enumeration defines constants that describe the status of a stream. These values are returned by CFReadStreamGetStatus and CFWriteStreamGetStatus.

CFStream Error Domain Constants

Defines constants for values returned in the domain field of the CFStreamError structure. (Deprecated. These constants are returned by CFReadStreamGetError and CFWriteStreamGetError; use CFReadStreamCopyError and CFWriteStreamCopyError instead.)

typedef enum {
   kCFStreamErrorDomainCustom = -1,
   kCFStreamErrorDomainPOSIX = 1,
   kCFStreamErrorDomainMacOSStatus,
} CFStreamErrorDomain;

Constants

kCFStreamErrorDomainCustom

The error code is a custom error code.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamErrorDomainPOSIX

The error code is an error code defined in errno.h.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamErrorDomainMacOSStatus

The error is an OSStatus value defined in MacErrors.h.

Available in iOS 2.0 and later.

Declared in CFStream.h.

Discussion

These constants indicate how the error code in the error field in the CFStreamError structure should be interpreted.

CFStream Error Domain Constants (CFHost)

Defines constants for values returned in the domain field of the CFStreamError structure.

const SInt32 kCFStreamErrorDomainNetDB;
const SInt32 kCFStreamErrorDomainNetServices;
const SInt32 kCFstreamErrorDomainMach;
const SInt32 kCFStreamErrorDomainFTP;
const SInt32 kCFStreamErrorDomainHTTP;
const int kCFStreamErrorDomainSOCKS;
const SInt32 kCFStreamErrorDomainSystemConfiguration;
const int kCFStreamErrorDomainSSL;

Constants

kCFStreamErrorDomainNetDB

The error code is an error code defined in netdb.h.

Available in iOS 2.0 and later.

Declared in CFHost.h.

kCFStreamErrorDomainNetServices

The error code is a CFNetService error code. For details, see the CFNetService Error Constants enumeration.

Available in iOS 2.0 and later.

Declared in CFNetServices.h.

kCFStreamErrorDomainMach

The error code is a Mach error code defined in mach/error.h.

Available in iOS 2.0 and later.

Declared in CFNetServices.h.

kCFStreamErrorDomainFTP

The error code is an FTP error code.

Available in iOS 2.0 and later.

Declared in CFFTPStream.h.

kCFStreamErrorDomainHTTP

The error code is an HTTP error code.

Available in iOS 2.0 and later.

Declared in CFHTTPStream.h.

kCFStreamErrorDomainSOCKS

The error code is a SOCKS proxy error.

Available in iOS 2.0 and later.

Declared in CFSocketStream.h.

kCFStreamErrorDomainSystemConfiguration

The error code is a system configuration error code as defined in System/ConfigurationSystemConfiguration.h.

Available in iOS 2.0 and later.

Declared in CFHost.h.

kCFStreamErrorDomainSSL

The error code is an SSL error code as defined in Security/SecureTransport.h.

Available in iOS 2.0 and later.

Declared in CFSocketStream.h.

Discussion

These constants indicate how the error code in the error field in the CFStreamError structure should be interpreted.

CFStream Event Type Constants

Defines constants for stream-related events.

typedef enum {
kCFStreamEventNone = 0,
kCFStreamEventOpenCompleted = 1,
kCFStreamEventHasBytesAvailable = 2,
kCFStreamEventCanAcceptBytes = 4,
kCFStreamEventErrorOccurred = 8,
kCFStreamEventEndEncountered = 16
} CFStreamEventType;

Constants

kCFStreamEventNone

No event has occurred.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamEventOpenCompleted

The open has completed successfully.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamEventHasBytesAvailable

The stream has bytes to be read.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamEventCanAcceptBytes

The stream can accept bytes for writing.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamEventErrorOccurred

An error has occurred on the stream.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamEventEndEncountered

The end of the stream has been reached.

Available in iOS 2.0 and later.

Declared in CFStream.h.

Discussion

This enumeration defines constants for stream-related events.

Stream Properties

Stream property names that can be set or copied.

const CFStringRef kCFStreamPropertyAppendToFile;
const CFStringRef kCFStreamPropertyFileCurrentOffset;
const CFStringRef kCFStreamPropertyDataWritten;
const CFStringRef kCFStreamPropertySocketNativeHandle;
const CFStringRef kCFStreamPropertySocketRemoteHostName;
const CFStringRef kCFStreamPropertySocketRemotePortNumber;

Constants

kCFStreamPropertyDataWritten

Value is a CFData object that contains all the bytes written to a writable memory stream. You cannot modify this value.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamPropertyAppendToFile

Value is a CFBoolean value that indicates whether to append the written data to a file, if it already exists, rather than to replace its contents.

You must set this value before opening the writable file stream. The default value is kCFBooleanFalse, indicating that the stream should replace any pre-existing file. You cannot read this value.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamPropertyFileCurrentOffset

Value is a CFNumber object containing the current file offset.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamPropertySocketNativeHandle

Value is a CFData object that contains the native handle for a socket stream—of type CFSocketNativeHandle—to which the socket stream is connected.

This property is only available for socket streams. You cannot modify this value. You can read this value at any time.

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamPropertySocketRemoteHostName

Value is a CFString object containing the name of the host to which the socket stream is connected or NULL if unknown.

You cannot modify this value. You can read this value at any time.]

Available in iOS 2.0 and later.

Declared in CFStream.h.

kCFStreamPropertySocketRemotePortNumber

Value is a CFNumber object containing the remote port number to which the socket stream is connected or NULL if unknown.

You cannot modify this value. You can read this value at any time.]

Available in iOS 2.0 and later.

Declared in CFStream.h.

Discussion

Use CFReadStreamCopyProperty or CFWriteStreamCopyProperty to read the property values. Use CFReadStreamSetProperty or CFWriteStreamSetProperty to set the property values.

Did this document help you?

Shop the Apple Online Store (1-800-MY-APPLE), visit an Apple Retail Store, or find a reseller.