Now, I'm developing on iPhone SDK3 and iPodTouch 2G. iPodTouch 2G can't do full function of iOS4. I want to change iPhone SDK4 development.In july, iPhone 4 and iPad will available in singapore. So, What should I buy iPad or iPhone 4 for iPhone SDK 4 ?
What different between iPad API and iPhone 4 API ? How about market ? Can I write iPhone app with iPad ?
I'm not experiences in ObjectiveC but I guess it really depends of what you want to do. You can do everything in the emulator so I guess you want the real devices to do proper testing over your applications. The only difference between both is that iPad doesn't have the new 6 axis acelerometer and doesn't have frontal camera. Apart from that the API should be the same (removing the support for phone calls oviously). I dont know what apple is going to do about games and so on but I guess the solution will be the same than between 3gs Iphone and IPad. Since the Ipad screen resolution is still bigger than the new Iphone one, you should be able to run any iPhone application (even the new ones) in your IPad (unless they use frontal camera or any other functionality not present in the iPad).
In resume, If you only want the device for development I whould buy an IPad since you can develop and test IPad and IPhone applications, so it is much more versatile. If you have an IPhone forget about testing IPad apps since you have not enough resolution.
Hope it helps.
The iPad runs iOS 3.2 currently. Apple has said that 4.0 won't be available for the iPad until "Fall" (aka Autumn). So if you want to test 4.0 apps in July on a real device (not just the simulator), you'll need an iPhone 3GS or 4.
Each version of the OS has the same API for all devices, but some of them don't support all all features. For example, the UIImagePickerController allows the user to select a photo. On an iPhone, they can take a picture with the camera or pick an existing photo from their Photo Library. With iPad and iPod Touch, there is no camera, so the user could only pick a picture from their Photo Library.
If you are relying on hardware features such as camera, compass, gyroscope, accelerometer for your application, you'd need a device that has this feature as the emulator does not them.
iPhone 4 has all of the hardware features of all iPhone, iPod Touch and iPad devices. Buying an iPhone 4 with or without contract is going to cost some money, but if you're developing an application you can recover the cost with sales of your app or iAd revenue.
If your application does not need specific hardware, then the best choice for you is going to depend on cost and whether you will use the device each day. A second-hand iPhone 3GS will do almost all iOS 4.0 features except front-facing camera and gyroscope.