IOS UDP通信

#import <UIKit/UIKit.h>

//包含了udp的socket(GCD/Blocks版本)
#import "GCDAsyncUdpSocket.h"

//这是一个接收 消息界面
@interface ViewController : UIViewController<GCDAsyncUdpSocketDelegate>{
    //udp对象
    GCDAsyncUdpSocket *udpServerSoket;
}
@end

#import "ViewController.h"
#import "SendViewController.h"

@interface ViewController ()

@end


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationItem.title = @"接收消息";
    [self showNavItem];
    [self createUdpSocket];
    
}
-(void)showNavItem{
    UIBarButtonItem *sendMyself = [[UIBarButtonItem alloc] initWithTitle:@"发送本身" style:UIBarButtonItemStylePlain target:self action:@selector(sendMyself)];
    self.navigationItem.rightBarButtonItem = sendMyself;
}

-(void)sendMyself{
    SendViewController *svc = [[SendViewController alloc] init];
    [self.navigationController pushViewController:svc animated:YES];
}

-(void) createUdpSocket{
    //建立一个后台队列 等待接收数据
    dispatch_queue_t dQueue = dispatch_queue_create("My socket queue", NULL); //第一个参数是该队列的名字
    //1.实例化一个udp socket套接字对象
    // udpServerSocket须要用来接收数据
    udpServerSoket = [[GCDAsyncUdpSocket alloc]initWithDelegate:self delegateQueue:dQueue socketQueue:nil];
    
    //2.服务器端来监听端口12345(等待端口12345的数据)
    [udpServerSoket bindToPort:12345 error:nil];
    
    //3.接收一次消息(启动一个等待接收,且只接收一次)
    [udpServerSoket receiveOnce:nil];
}

#pragma mark -GCDAsyncUdpSocketDelegate
-(void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data fromAddress:(NSData *)address withFilterContext:(id)filterContex
{
    //取得发送发的ip和端口
    NSString *ip = [GCDAsyncUdpSocket hostFromAddress:address];
    uint16_t port = [GCDAsyncUdpSocket portFromAddress:address];
    
    //data就是接收的数据
    NSString *s = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    
    NSLog(@"[%@:%u]%@",ip, port,s);
    
    [self sendBackToHost: ip port:port withMessage:s];
    //再次启动一个等待
    [udpServerSoket receiveOnce:nil];
}
-(void)sendBackToHost:(NSString *)ip port:(uint16_t)port withMessage:(NSString *)s{
    NSString *msg = @"我已接收到消息";
    NSData *data = [msg dataUsingEncoding:NSUTF8StringEncoding];
    
    [udpServerSoket sendData:data toHost:ip port:port withTimeout:60 tag:200];
}


@end

#import <UIKit/UIKit.h>
#import "GCDAsyncUdpSocket.h"

@interface SendViewController : UIViewController<GCDAsyncUdpSocketDelegate>{
    //这个socket用来作发送使用 固然也能够接收
    GCDAsyncUdpSocket *sendUdpSocket;
}
@end

#import "SendViewController.h"

@implementation SendViewController

-(void)viewDidLoad{
    [super viewDidLoad];
    self.navigationItem.title = @"发送";
    self.view.backgroundColor = [UIColor whiteColor];
    [self showNavItem];
    [self createClientUdpSocket];
}

- (void) showNavItem {
    UIBarButtonItem *sendMsg = [[UIBarButtonItem alloc] initWithTitle:@"发送消息" style:UIBarButtonItemStylePlain target:self action:@selector(sendMsg)];
    self.navigationItem.rightBarButtonItem = sendMsg;
}

-(void)createClientUdpSocket{
    dispatch_queue_t dQueue = dispatch_queue_create("client udp socket", NULL);
    
    //1.建立一个 udp socket用来和服务器端进行通信
    sendUdpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dQueue socketQueue:nil];
    
    //2.banding一个端口(可选),若是不绑定端口, 那么就会随机产生一个随机的电脑惟一的端口
        //端口数字范围(1024,2^16-1)
    [sendUdpSocket bindToPort:8085 error:nil];
    
    //3.等待接收对方的消息
    [sendUdpSocket receiveOnce:nil];
}

- (void) sendMsg {
    NSString *s = @"hello IOS";
    NSData *data = [s dataUsingEncoding:NSUTF8StringEncoding];
    NSString *host = @"10.0.161.87";
    uint16_t port = 12345;
    
    //开始发送
    //改函数只是启动一次发送 它自己不进行数据的发送, 而是让后台的线程慢慢的发送 也就是说这个函数调用完成后,数据并无马上发送,异步发送
    [sendUdpSocket sendData:data toHost:host port:port withTimeout:60 tag:100];
}

#pragma mark -GCDAsyncUdpSocketDelegate
-(void)udpSocket:(GCDAsyncUdpSocket *)sock didSendDataWithTag:(long)tag{
    if (tag == 100) {
        //NSLog(@"表示标记为100的数据发送完成了");
    }
}
-(void)udpSocket:(GCDAsyncUdpSocket *)sock didNotSendDataWithTag:(long)tag dueToError:(NSError *)error{
    NSLog(@"标记为tag %ld的发送失败 失败缘由 %@",tag, error);
}

-(void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data fromAddress:(NSData *)address withFilterContext:(id)filterContext{
    NSString *ip = [GCDAsyncUdpSocket hostFromAddress:address];
    uint16_t port = [GCDAsyncUdpSocket portFromAddress:address];
    NSString *s = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    // 继续来等待接收下一次消息
    NSLog(@"收到服务端的响应 [%@:%d] %@", ip, port, s);
    [sock receiveOnce:nil];
    
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [self sendBackToHost:ip port:port withMessage:s];
    });
}

-(void)sendBackToHost:(NSString *)ip port:(uint16_t)port withMessage:(NSString *)s{
    
    
    NSString *msg = @"我再发送消息";
    NSData *data = [msg dataUsingEncoding:NSUTF8StringEncoding];
    
    [sendUdpSocket sendData:data toHost:ip port:port withTimeout:60 tag:200];
}

-(void)dealloc{
    NSLog(@"%s",__func__ );
    [sendUdpSocket close];
    sendUdpSocket = nil;
}

@end