Android – How to use the paid version of the app as a “key” to the free version

androidkey

Let's say for example that I have some Android app that does X. The free version has ads or basic features. I want to have a paid version that removes the ads and adds extra features.

How can I use the paid app as a "license key" to unlock the features in the free app?

So the user would install the free app, then install the paid app to get the extra features, but they would still run the free app (which would now be unlocked). What's the best approach to doing this?

Best Answer

Use PackageManager to ensure your paid package is installed. AND ensure your free package signature matches installed premium package signature. Otherwise somebody would be able to install unsigned app with package name matching your paid package name and unlock premium this way.

This post can help you to find your signature Detect if app was downloaded from Android Market

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Javascript – How to efficiently count the number of keys/properties of an object in JavaScript

To do this in any ES5-compatible environment, such as Node.js, Chrome, Internet Explorer 9+, Firefox 4+, or Safari 5+:

Object.keys(obj).length

Browser compatibility
Object.keys documentation (includes a method you can add to non-ES5 browsers)

Android – How to close/hide the Android soft keyboard programmatically

You can force Android to hide the virtual keyboard using the InputMethodManager, calling hideSoftInputFromWindow, passing in the token of the window containing your focused view.

// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}

This will force the keyboard to be hidden in all situations. In some cases, you will want to pass in InputMethodManager.HIDE_IMPLICIT_ONLY as the second parameter to ensure you only hide the keyboard when the user didn't explicitly force it to appear (by holding down the menu).

Note: If you want to do this in Kotlin, use: context?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager

Kotlin Syntax

// Only runs if there is a view that is currently focused
this.currentFocus?.let { view ->
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(view.windowToken, 0)
}

Best Answer

Related Solutions

Javascript – How to efficiently count the number of keys/properties of an object in JavaScript

Android – How to close/hide the Android soft keyboard programmatically

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