activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hello World!"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            android:id="@+id/text" android:layout_marginTop="8dp"
            app:layout_constraintTop_toBottomOf="@+id/login_button" android:layout_marginBottom="8dp"
            app:layout_constraintBottom_toTopOf="@+id/imageView"/>

    <com.twitter.sdk.android.core.identity.TwitterLoginButton
            android:id="@+id/login_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
            app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
            android:layout_marginTop="200dp" app:layout_constraintTop_toTopOf="parent"/>
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" tools:srcCompat="@tools:sample/avatars"
            android:id="@+id/imageView"
            app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
            android:layout_marginBottom="200dp" app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"/>

</android.support.constraint.ConstraintLayout>