If you develop an app that gets data from web services you have to take into consideration that our iOS devices (iPhone, iPad) can be moved in a place with low signal.
When develop in XCode you can have the absolute control of the network connection.
The tool called Network Link Conditioner and is available in Lion and Mountain Lion OS X.
In addition to the default profiles, you can set custom bandwidth profiles to define a specific set of conditions for dropped packets, DNS delay, and uplink and downlink bandwidth.
In order to install it you have to download Hardware IO Tools for Xcode from Downloads fro Apple developers section in Apple's Developer site or from XCode App, select Open Developer Tool from menu and then click to More Developer Tools.
When you download the package, open it and double click on the file Network LinkConditioner.prefpane
Then you will find it on Other tab of System Preferences.
So it's easy to control the network connection at the same time as you test your app in simulator.
It's a great tool!