Here is some sample code from the previously mentioned AsyncSocket code that I modified into a class called SocketCommunicationManager.
A few things to note:
- Our messages are being delimited with newline characters (\n) so when reading data from the socket I had to make sure to use the right constant from the AsyncSocket class (LFData in our case). AsyncSocket also provides CRLFData, CRData, and ZeroData as predefined message delimiters.
- I set up the SocketCommunicationManager to always wait for an incoming message after I received and acted on a previous one. To accomplish that I used the
(void)readDataToData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag method. This method will wait until data is written to the socket, read up until the specified delimiter, and then call the delegate method (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag;
- The SocketCommunicationManager uses NSNotificationCenter to publish any messages received from the socket. These messages are named kNotification and the message is put into the userInfo dictionary using the kNotificationMessage key.
- Everything read from the socket is wrapped in an NSData object, so you'll have to decode that data after it is received.
Here's the code:
#import <Foundation/Foundation.h>
extern NSString * const kNotification;
extern NSString * const kNotificationMessage;
@class AsyncSocket;
@interface SocketCommunicationManager : NSObject {
AsyncSocket *socket;
BOOL isRunning;
NSNotificationCenter* notificationCenter;
}
@property (readwrite, assign) BOOL isRunning;
- (void)connectToHost:(NSString *)hostName onPort:(int)port;
- (void)sendMessage:(NSString *)message;
- (void)disconnect;
@end
#import "SocketCommunicationManager.h"
#import "AsyncSocket.h"
NSString * const kNotification = @"kNotification";
NSString * const kNotificationMessage = @"kNotificationMessage";
@implementation SocketCommunicationManager
@synthesize isRunning;
- (id) init {
if (!(self = [super init]))
return nil;
socket = [[AsyncSocket alloc] initWithDelegate:self];
[self setIsRunning:NO];
notificationCenter = [NSNotificationCenter defaultCenter];
return self;
}
- (void)connectToHost:(NSString *)hostName onPort:(int)port {
if (![self isRunning]) {
if (port < 0 || port > 65535)
port = 0;
NSError *error = nil;
if (![socket connectToHost:hostName onPort:port error:&error]) {
NSLog(@"Error connecting to server: %@", error);
return;
}
[self setIsRunning:YES];
} else {
[socket disconnect];
[self setIsRunning:false];
}
}
- (void)disconnect {
[socket disconnect];
}
- (void)dealloc {
[super dealloc];
[socket disconnect];
[socket dealloc];
}
- (void)sendMessage:(NSString *)message {
NSString *terminatedMessage = [message stringByAppendingString:@"\r\n"];
NSData *terminatedMessageData = [terminatedMessage dataUsingEncoding:NSASCIIStringEncoding];
[socket writeData:terminatedMessageData withTimeout:-1 tag:0];
}
#pragma mark AsyncSocket Delegate
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port {
NSLog(@"Connected to server %@:%hu", host, port);
[sock readDataToData:[AsyncSocket LFData] withTimeout:-1 tag:0];
}
- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag {
NSData *truncatedData = [data subdataWithRange:NSMakeRange(0, [data length] - 1)];
NSString *message = [[[NSString alloc] initWithData:truncatedData encoding:NSASCIIStringEncoding] autorelease];
if (message)
NSLog(@"%@", message);
else
NSLog(@"Error converting received data into UTF-8 String");
NSDictionary *userInfo = [NSDictionary dictionaryWithObject:message forKey:kNotificationMessage];
[notificationCenter postNotificationName:kNotification object:self userInfo:userInfo];
[sock readDataToData:[AsyncSocket LFData] withTimeout:-1 tag:0];
}
- (void)onSocket:(AsyncSocket *)sock didWriteDataWithTag:(long)tag {
[sock readDataToData:[AsyncSocket LFData] withTimeout:-1 tag:0];
}
- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err {
NSLog(@"Client Disconnected: %@:%hu", [sock connectedHost], [sock connectedPort]);
}
@end
