Network Problem - Help 4 Bachelor Thesis

[NomenNescio]

Hello everybody!

I hope you can help me with my problem, I have to solve.
I need to set up a communication between a Java based server and an iPhone (via WiFi).
The server works perfectly and without errors, nevertheless, her is the code of it:

public static boolean initServer(int port) {
		System.out.println("Starting Server on: "+getIP()+":"+ port);
		boolean success = false;
		
		try {
			serverSocket = new ServerSocket(port);
			success = true;
	        try {
	            clientSocket = serverSocket.accept();
	            } catch (IOException e) {
	            	System.err.println("Accept failed.");
	        }
		} catch (IOException e) {
			System.err.println("Could not listen on port: " + port+ ".");
		}
		return success;
	}
	/**
	 * Generates a PrintWriter for Reading the clients data
	 * @return The PrintWriter
	 */
	public static PrintWriter getPrintWriter() {
		
        try {
            out = new PrintWriter(clientSocket.getOutputStream(), true);
        } catch (IOException e) {
            System.err.println("Could not generate PrintWriter.");
        }
        
        return out;
	}
	/**
	 * Generates a BufferedReader for sending data to the client
	 * @return The BufferedReader
	 */
	public static BufferedReader getBufferedReader() {
		 
		try {
			in = new BufferedReader(
						new InputStreamReader(
						clientSocket.getInputStream()));
		} catch (IOException e) {
            System.err.println("Could not generate BufferedReader.");
		}
		 return in;
	}

For the iPhoneApp i referred to this article by apple: Technical Q&A QA1652: Using NSStreams For A TCP Connection Without NSHost

My App connects to the server, but when I try to send to or receive from the server, the App and the iPhoneSimulator both crush.

Has anybody an idea, where I went wrong?
Is there a better way, to set up a communication?

Thank you for your help,

NomenNescio