Sencha Touch is a great framework, but requires a LOT getting used to. The officials Docs do not always have the answer you’re looking for. ST forums and stackoverflow are excellent resources to consult when in need.
If you are a web developer, DO NOT waste time learning Objective-C or Java for creating native iOS and Android apps. Instead use something like ST to develop a mobile web app, and then convert it into a native app using Cordova / PhoneGap.
Cordova is the renamed, open-source version of PhoneGap.
If your app is data-centeric, most probably it will depend on a webservice / API. If the API and the app are hosted on the same server, no problemo. In case of native apps, that are basically web apps PhoneGapped into native apps, that’d mean calling a remote API, and that is the problem. See same origin policy.
Most googled solutions will point to making the service JSONP supported; but JSONP works only for GET requests. CORS is a recent W3C standard that supports all HTTP methods, but it still doesn’t work for PhoneGapped apps. ASP.NET Web API provides an easy CORS implementation.
The perfect solution is to keep making Ajax calls normally, but using the full URL of the remote API. That will work because a PhoneGapped app doesn’t render in a browser but in a WebView (through a file:// URL). So it’s not restricted by browser’s same origin policy.
You may frequently encounter annoying cache issues with PhoneGapped apps. Just place a super.clearCache() in your Android app’s main activity’s onCreate().
A PhoneGapped iOS app will run in fullscreen mode, by default, such that the status bar in iOS 7+ will appear over it. A fix is right here!
One can create an IPA archive for testing on iOS devices via Build > *.app > iTunes > ?*.ipa. Believe me, it’s one of the most stupid things you will ever do. This is the correct way to create IPA archives for ad hoc distribution.