It's certainly possible to develop on a Windows machine, in fact, my first application was exclusively developed on the old Dell Precision I had at the time :)
There are three routes;
- Install OSx86 (aka iATKOS / Kalyway) on a second partition/disk and dual boot.
- Run Mac OS X Server under VMWare (Mac OS X 10.7 (Lion) onwards, read the update below).
- Use Delphi XE4 and the macincloud service. This is a commercial toolset, but the component and lib support is growing.
The first route requires modifying (or using a pre-modified) image of Leopard that can be installed on a regular PC. This is not as hard as you would think, although your success/effort ratio will depend upon how closely the hardware in your PC matches that in Mac hardware - e.g. if you're running a Core 2 Duo on an Intel Motherboard, with an NVidia graphics card you are laughing. If you're running an AMD machine or something without SSE3 it gets a little more involved.
If you purchase (or already own) a version of Leopard then this is a gray area since the Leopard EULA states you may only run it on an "Apple Labeled" machine. As many point out if you stick an Apple sticker on your PC you're probably covered.
The second option is more costly. The EULA for the workstation version of Leopard prevents it from being run under emulation and as a result, there's no support in VMWare for this. Leopard server, however, CAN be run under emulation and can be used for desktop purposes. Leopard server and VMWare are expensive, however.
If you're interested in option 1) I would suggest starting at Insanelymac and reading the OSx86 sections.
I do think you should consider whether the time you will invest is going to be worth the money you will save though. It was for me because I enjoy tinkering with this type of stuff and I started during the early iPhone betas, months before their App Store became available.
Alternatively, you could pick up a low-spec Mac Mini from eBay. You don't need much horsepower to run the SDK and you can always sell it on later if you decide to stop development or buy a better Mac.
Update: You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier. Apple does not allow these Client OSes to be virtualized. With Mac OS X 10.7 (Lion) onwards, Apple has changed its licensing agreement in regards to virtualization. Source: VMWare KnowledgeBase
New answer, powershell
TCP
Get-Process -Id (Get-NetTCPConnection -LocalPort YourPortNumberHere).OwningProcess
UDP
Get-Process -Id (Get-NetUDPEndpoint -LocalPort YourPortNumberHere).OwningProcess
Old answer, cmd
C:\> netstat -a -b
(Add -n to stop it trying to resolve hostnames, which will make it a lot faster.)
Note Dane's recommendation for TCPView. It looks very useful!
-a Displays all connections and listening ports.
-b Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.
-n Displays addresses and port numbers in numerical form.
-o Displays the owning process ID associated with each connection.
Best Answer
Expanding on the two previous answers, if you just want Objective-C but not any of the Cocoa frameworks, then gcc will work on any platform. You can use it through Cygwin or get MinGW. However, if you want the Cocoa frameworks, or at least a reasonable subset of them, then GNUStep and Cocotron are your best bets.
Cocotron implements a lot of stuff that GNUStep does not, such as CoreGraphics and CoreData, though I can't vouch for how complete their implementation is on a specific framework. Their aim is to keep Cocotron up to date with the latest version of OS X so that any viable OS X program can run on Windows. Because GNUStep typically uses the latest version of gcc, they also add in support for Objective-C++ and a lot of the Objective-C 2.0 features.
I haven't tested those features with GNUStep, but if you use a sufficiently new version of gcc, you might be able to use them. I was not able to use Objective-C++ with GNUStep a few years ago. However, GNUStep does compile from just about any platform. Cocotron is a very mac-centric project. Although it is probably possible to compile it on other platforms, it comes XCode project files, not makefiles, so you can only compile its frameworks out of the box on OS X. It also comes with instructions on compiling Windows apps on XCode, but not any other platform. Basically, it's probably possible to set up a Windows development environment for Cocotron, but it's not as easy as setting one up for GNUStep, and you'll be on your own, so GNUStep is definitely the way to go if you're developing on Windows as opposed to just for Windows.
For what it's worth, Cocotron is licensed under the MIT license, and GNUStep is licensed under the LGPL.