iOS网络编程之Socket

一，iOS网络编程层次模型

二，BSD socket API 简介

int socket(int addressFamily, int type,
int protocol)

int close(int socketFileDescriptor)

int bind(int socketFileDescriptor,
sockaddr *addressToBind,
int addressStructLength) 

int accept(int socketFileDescriptor,
sockaddr *clientAddress, int
clientAddressStructLength)

int connect(int socketFileDescriptor,
sockaddr *serverAddress, int
serverAddressLength)

hostent* gethostbyname(char *hostname)

int send(int socketFileDescriptor, char
*buffer, int bufferLength, int flags)

int receive(int socketFileDescriptor, char
*buffer, int bufferLength, int flags)

int sendto(int socketFileDescriptor,
char *buffer, int bufferLength, int
flags, sockaddr *destinationAddress, int
destinationAddressLength)

int recvfrom(int socketFileDescriptor,
char *buffer, int bufferLength, int
flags, sockaddr *fromAddress, int
*fromAddressLength)

三，服务器工作流程

四，客户端工作流程

五，客户端代码示例

- (void)loadDataFromServerWithURL:(NSURL *)url
{
NSString * host = [url host];
NSNumber * port = [url port];

// Create socket
//
int socketFileDescriptor = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == socketFileDescriptor) {
NSLog(@"Failed to create socket.");
return;
}

// Get IP address from host
//
struct hostent * remoteHostEnt = gethostbyname([host UTF8String]);
if (NULL == remoteHostEnt) {
close(socketFileDescriptor);

[self networkFailedWithErrorMessage:@"Unable to resolve the hostname of the warehouse server."];
return;
}

struct in_addr * remoteInAddr = (struct in_addr *)remoteHostEnt->h_addr_list[0];

// Set the socket parameters
//
struct sockaddr_in socketParameters;
socketParameters.sin_family = AF_INET;
socketParameters.sin_addr = *remoteInAddr;
socketParameters.sin_port = htons([port intValue]);

// Connect the socket
//
int ret = connect(socketFileDescriptor, (struct sockaddr *) &socketParameters, sizeof(socketParameters));
if (-1 == ret) {
close(socketFileDescriptor);

NSString * errorInfo = [NSString stringWithFormat:@" >> Failed to connect to %@:%@", host, port];
[self networkFailedWithErrorMessage:errorInfo];
return;
}

NSLog(@" >> Successfully connected to %@:%@", host, port);

NSMutableData * data = [[NSMutableData alloc] init];
BOOL waitingForData = YES;

// Continually receive data until we reach the end of the data
//
int maxCount = 5;   // just for test.
int i = 0;
while (waitingForData && i < maxCount) {
const char * buffer[1024];
int length = sizeof(buffer);

// Read a buffer's amount of data from the socket; the number of bytes read is returned
//
int result = recv(socketFileDescriptor, &buffer, length, 0);
if (result > 0) {
[data appendBytes:buffer length:result];
}
else {
// if we didn't get any data, stop the receive loop
//
waitingForData = NO;
}

++i;
}

// Close the socket
//
close(socketFileDescriptor);

[self networkSucceedWithData:data];
}

NSThread * backgroundThread = [[NSThread alloc] initWithTarget:self
selector:@selector(loadDataFromServerWithURL:)
object:url];
[backgroundThread start];

- (void)networkFailedWithErrorMessage:(NSString *)message
{
// Update UI
//
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
NSLog(@"%@", message);

self.receiveTextView.text = message;
self.connectButton.enabled = YES;
[self.networkActivityView stopAnimating];
}];
}

- (void)networkSucceedWithData:(NSData *)data
{
// Update UI
//
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
NSString * resultsString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@" >> Received string: '%@'", resultsString);

self.receiveTextView.text = resultsString;
self.connectButton.enabled = YES;
[self.networkActivityView stopAnimating];
}];
}