Sethathi

# Which dispatcher should be used for which use case?

## Dispatchers
a) Dispatchers.Main
b) Dispatchers.IO
c) Dispatchers.Default

Sethathi

<!-- What's wrong with this layout, how can it be improve? -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.appcompat.widget.LinearLayoutCompat
        android:id="@+id/fullnameLayout"

Sethathi

<!-- How could we optimise this? -->
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/tv_top"
        android:text="Full Name"

Sethathi

// 1. What would happen if a user pressed back button before `fetchProfileDetailsFromServer` completes
// 2. How can we improve this code?
class ProfileActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_profile)

        loadProfileDetails()
    }

Sethathi

// `BookingsActivity` is rotatable and currently loads bookings from API on each rotation. How can we prevent this from happening? 
class BookingViewModel(
    private val repository: BookingsRepository
) : ViewModel() {

    // We want to make sure that this is only settable privately.
    val bookings = MutableLiveData<List<Booking>>()

    fun loadBookings() {
        val bookings = repository.getBookings()

Sethathi

// Can you spot any issues with code?
class MyBroadcastReceiverActivity : AppCompatActivity() {
    private var broadcastReceiver: BroadcastReceiver? = null
    override fun onCreate(@Nullable savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_one)
    }

    private fun registerBroadCastReceiver() {
        broadcastReceiver = object : BroadcastReceiver() {

Sethathi

// Why won't this compile?
var name: String?

if name != nil {
   displayName(name: name)
}

func displayName(name: String) {
   // display name
}

Sethathi

// What will be displayed by this code?
blueSquare.backgroundColor = UIColor.blue
redSquare.backgroundColor = UIColor.red

let constraints = [
    redSquare.topAnchor.constraint(equalTo: blueSquare.topAnchor),
    blueSquare.leftAnchor.constraint(equalTo: redSquare.leftAnchor, constant: -40),
    blueSquare.bottomAnchor.constraint(equalTo: redSquare.bottomAnchor),
    redSquare.rightAnchor.constraint(equalTo: blueSquare.rightAnchor, constant: -40)
]

Sethathi

// What's the output of this code?
extension Int {
    func times(callback: (_ n: Int) -> ()) {
        for n in 0...self {
            callback(n)
        }
    }
}

2.times { (n) in

Sethathi

// How can this conditional be simplified?
let price = 5

if price >= 1 && price <= 5 {
   print("Price within range")
}