AsyncUdpSocket how to use receive

Question

I am trying to get a program for iPhone running on the simulator. My problem is with receiving UDP data. I use asyncUdpSocket. If I make a socket and use sendData:(NSD

Answer 1

Not sure if this will be helpful, but I had the same problem, and here is how I fixed it.

In my case, the problem was that:

[self.socket receiveWithTimeout:-1 tag:0];

was located in the "wrong" place.

If you call [self.socket receiveWithTimeout:-1 tag:0]; in the method didFinishLaunchingWithOptions, the socket won't work regardless of what you do (even if you try launching it in a new thread). To fix this issue, I made a button and moved the receiveWithTimeout call to a method called when the button is clicked. My guess is that ASyncUdpSocket doesn't like something about the thread handling in didFinishLaunchingWithOptions.

I have posted my working sample code below (using XCode 5.1.1). These are the complete AppDelegate files for my Xcode project.

AppDelegate.h

#import 
#import "AsyncUdpSocket.h"

@interface AppDelegate : UIResponder 

@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) AsyncUdpSocket *udpSocket;
@property (strong, nonatomic) UILabel *receiver;

@end

AppDelegate.m

#import "AppDelegate.h"
#import "AsyncUdpSocket.h"
#import 
#import 

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Create the main window
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];

    // Create a label for showing received text
    self.receiver = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320, 80.0)];
    self.receiver.text  = @"No message, yet!";
    self.receiver.textColor       = [UIColor blackColor];
    [self.window addSubview:self.receiver];

    // Create a button for sending messages
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setFrame:CGRectMake(80.0, 210.0, 160.0, 40.0)];
    [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
    [button setTitle:@"Start Game" forState:UIControlStateNormal];
    [button setBackgroundColor:[UIColor blueColor]];
    [self.window addSubview:button];

    @try {
        self.udpSocket = [[AsyncUdpSocket alloc] initWithDelegate:self];
        if (![self.serverSocket bindToPort:9003 error:nil]) {
            NSLog(@"COULD NOT BIND TO PORT");
        }
        if (![self.udpSocket enableBroadcast:YES error:nil]) {
            NSLog(@"COULD NOT ENABLE BROADCASTING");
        }
    } @catch (NSException * e) {
        NSLog(@"Exception: %@", e);
    }
    return YES;
}

- (void)buttonClick:(UIButton*)button {
    NSData * data = [@"Hello World" dataUsingEncoding:NSUTF8StringEncoding];
    [self.udpSocket receiveWithTimeout:-1 tag:0];
    if (![self.udpSocket sendData:data toHost:@"127.0.0.1" port:9003 withTimeout:0.2 tag:1]) {
        NSLog(@"COULD NOT SEND DATA");
    } else {
        NSLog(@"Sent packet (from %@:%d to 127.0.0.1:9001)", self.udpSocket.localHost, self.udpSocket.localPort);
    }
}

- (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port {
    NSLog(@"    Received data (from %@:%d) - %@", host, port, data);
    self.receiver.text = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
    [self.udpSocket receiveWithTimeout:-1 tag:0];

    return YES;
}

@end

Hope this is helpful to someone.