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Q:

Explain the correct way to manage Outlets memory?

Answer

Create them as properties in the header that are retained. In the viewDidUnload set the outlets to nil(i.e self.outlet = nil). Finally in dealloc make sure to release the outlet.

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Subject: Application Development

Q:

If I call performSelector:withObject:afterDelay: – is the object retained?

Answer

Yes the object is retained. It creates a timer that calls a selector on the current threads run loop. It may not be 100% precise time-wise as it attempts to dequeue the message from the run loop and perform the selector.

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Subject: Application Development

Q:

Whats the difference between a NSArray and a NSMutableArray?

Answer

A NSArray’s contents can not be modified once it’s been created whereas a NSMutableArray can be modified as needed, i.e items can be added/removed from it.

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Subject: Application Development

Q:

How will you launch an Activity within you application?

Answer

For launching an application, we will need to create an intent that explicitly defines the activity that we wish to start. For example:


Code


        Intent intent = new Intent(this, MyTestActivity.class);


        startActivity(intent);

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Subject: Application Development

Q:

How can your application perform actions that are provided by other application e.g. sending email?

Answer

Intents are created to define an action that we want to perform and the launches the appropriate activity from another application.


Code


        Intent intent = new Intent(Intent.ACTION_SEND);


        intent.putExtra(Intent.EXTRA_EMAIL, recipientArray);


        startActivity(intent);

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Subject: Application Development

Q:

Write code snippet to retrieve IMEI number of Android phone?

Answer

TelephonyManager class can be used to get the IMEI number. It provides access to information about the telephony services on the device.


Code


        TelephonyManager mTelephonyMgr = (TelephonyManager)


        getSystemService(Context.TELEPHONY_SERVICE);


        String imei = mTelephonyMgr.getDeviceId();

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Subject: Application Development

Q:

How does an application run in isolation from other applications?

Answer

Each application gets its own Linux user ID and virtual machine which means that the application code runs in isolation from other applications.

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Subject: Application Development

Q:

Why cannot you run standard Java bytecode on Android?

Answer

Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java class files into Dalvik Executable files using an Android tool called "dx". In normal circumstances, developers will not be using this tool directly and build tools will care for the generation of DVM compatible files.

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Subject: Application Development