I want to develop app and games on IOS platform。
Can I use a iPod Touch 4 to develop games for iPhone and iPod Touch? ( leave out the hardware difference, like GPS or phone call )
If it could, when I complete my app and debugged with iPod Touch, is it has some limit to publish my app in Apple App Store?
You can use an iPod Touch to do the hardware debugging (as long as you aren’t using iPhone specific hardware), there is no requirement for an iPhone, you can also use the simulator to help debug. Apple has no limitation on requiring you to debug on an iPhone.
In Short, Yes you can develop without testing on an iPhone and publish to the app store with no issues.