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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 287 · 40 questions
TalentJR

Developer's tip (When this, do that): Event → handler → action: “on tap, do this”. The handler runs once for every tap. Counter: start + taps × step. A limit stops it growing; on = !on flips ON / OFF.

NameDateTime takenScore ___ / 40
  1. 1.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a timer event (c) a text event (d) a load event
  2. 2.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  3. 3.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  4. 4.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 8;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  5. 5.👆 The user taps the button 2 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) OFF (b) ON
  6. 6.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 6;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  7. 7.👆 What kind of event is this: a countdown hits zero? (a) a tap event (b) a text event (c) a load event (d) a timer event
  8. 8.👆 The user taps the button 5 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) OFF (b) ON
  9. 9.👆 A tap handler runs how many times if the user taps 4 times? (a) 8 (b) 1 (c) 4 (d) 0
  10. 10.👆 An event in an app is ___. (a) an app store (b) something that happens (c) a colour theme (d) a kind of list
  11. 11.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, nameBox.text! (b) Aman (c) Hello, Aman! (d) Hello!
  12. 12.True or false: the user types a letter is a text event. (a) True (b) False
  13. 13.True or false: the search box changes is a timer event. (a) False (b) True
  14. 14.True or false: the user taps Play is a tap event. (a) True (b) False
  15. 15.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  16. 16.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome, nameBox.text! (b) Welcome! (c) Riya (d) Welcome, Riya!
  17. 17.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a timer event (c) a text event (d) a load event
  18. 18.👆 What kind of event is this: the user taps Play? (a) a tap event (b) a load event (c) a text event (d) a timer event
  19. 19.👆 Which of these is an event? (a) the icon colour (b) a list of names (c) the font size (d) the user taps a button
  20. 20.👆 Code that runs when an event happens is called a ___. (a) headline (b) hashtag (c) header (d) handler
  21. 21.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 3;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  22. 22.👆 The user types Arjun in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Arjun (b) Welcome! (c) Welcome, nameBox.text! (d) Welcome, Arjun!
  23. 23.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 8;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  24. 24.👆 The user types Arjun in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello! (b) Hello, Arjun! (c) Hello, nameBox.text! (d) Arjun
  25. 25.👆 The user taps the button 2 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  26. 26.👆 What kind of event is this: the user types a letter? (a) a tap event (b) a timer event (c) a text event (d) a load event
  27. 27.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  28. 28.👆 The user taps the button 3 times. What number does the label show now?
    let points = 2;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  29. 29.👆 The user taps the button 3 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) OFF (b) ON
  30. 30.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 10;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  31. 31.👆 The user taps the button 4 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) ON (b) OFF
  32. 32.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  33. 33.👆 What kind of event is this: the app starts up? (a) a load event (b) a tap event (c) a timer event (d) a text event
  34. 34.👆 The user taps the button 4 times. What number does the label show now?
    let points = 9;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  35. 35.True or false: a countdown hits zero is a load event. (a) False (b) True
  36. 36.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) a charger (d) an action
  37. 37.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Zoya (b) Welcome! (c) Welcome, Zoya! (d) Welcome, nameBox.text!
  38. 38.👆 The user taps the button 2 times. What number does the label show now?
    let points = 8;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  39. 39.True or false: the app starts up is a text event. (a) False (b) True
  40. 40.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };

Answer key

  1. a load event
  2. 5
  3. 2
  4. 26
  5. OFF
  6. 10
  7. a timer event
  8. ON
  9. 4
  10. something that happens
  11. Hello, Aman!
  12. True
  13. False
  14. True
  15. 3
  16. Welcome, Riya!
  17. a timer event
  18. a tap event
  19. the user taps a button
  20. handler
  21. 18
  22. Welcome, Arjun!
  23. 20
  24. Hello, Arjun!
  25. 4
  26. a text event
  27. 3
  28. 8
  29. ON
  30. 35
  31. OFF
  32. 21
  33. a load event
  34. 17
  35. False
  36. an action
  37. Welcome, Zoya!
  38. 16
  39. False
  40. 1

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