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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 108 · 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.True or false: the user taps Play is a tap event. (a) True (b) False
  2. 2.👆 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
  3. 3.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 7;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  4. 4.👆 What kind of event is this: the user presses Save? (a) a timer event (b) a text event (c) a load event (d) a tap event
  5. 5.👆 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;
    };
  6. 6.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 1 (c) 8 (d) 4
  7. 7.👆 The user taps the button 2 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  8. 8.👆 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
  9. 9.👆 The user taps the button 2 times. What number does the label show now?
    let score = 2;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  10. 10.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  11. 11.👆 “On tap → do this” links an event to ___. (a) an action (b) a charger (c) a web address (d) a font
  12. 12.👆 An event in an app is ___. (a) a colour theme (b) a kind of list (c) an app store (d) something that happens
  13. 13.True or false: a countdown hits zero is a load event. (a) False (b) True
  14. 14.👆 The user taps the button 6 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  15. 15.👆 The user taps the button 6 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  16. 16.👆 What kind of event is this: the app starts up? (a) a load event (b) a timer event (c) a tap event (d) a text event
  17. 17.True or false: the user presses Save is a load event. (a) True (b) False
  18. 18.👆 What kind of event is this: a finger hits Like? (a) a tap event (b) a timer event (c) a load event (d) a text event
  19. 19.True or false: a finger hits Like is a timer event. (a) False (b) True
  20. 20.👆 What kind of event is this: a 5-minute alarm ends? (a) a load event (b) a timer event (c) a tap event (d) a text event
  21. 21.👆 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) Welcome, Zoya! (b) Welcome! (c) Welcome, nameBox.text! (d) Zoya
  22. 22.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 7;
    button.onTap = function () {
      stars = stars + 2;
      label.text = stars;
    };
  23. 23.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  24. 24.👆 The user taps the button 6 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  25. 25.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  26. 26.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 9;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  27. 27.👆 What kind of event is this: the screen first opens? (a) a text event (b) a tap event (c) a timer event (d) a load event
  28. 28.👆 The user taps the button 4 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  29. 29.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Well done, " + nameBox.text + "!";
    };     (a) Well done, nameBox.text! (b) Well done! (c) Meera (d) Well done, Meera!
  30. 30.👆 What kind of event is this: a countdown hits zero? (a) a text event (b) a timer event (c) a load event (d) a tap event
  31. 31.True or false: the app starts up is a timer event. (a) False (b) True
  32. 32.👆 The user taps the button 3 times. What number does the label show now?
    let points = 2;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  33. 33.True or false: the user types a letter is a text event. (a) False (b) True
  34. 34.👆 The user types Kabir 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) Hello, Kabir! (c) Hello! (d) Kabir
  35. 35.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  36. 36.👆 The user taps the button 6 times. What number does the label show now?
    let score = 5;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  37. 37.👆 The user taps the button 6 times. What number does the label show now?
    let stars = 3;
    button.onTap = function () {
      stars = stars + 1;
      label.text = stars;
    };
  38. 38.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi, nameBox.text! (b) Riya (c) Hi, Riya! (d) Hi!
  39. 39.👆 The user taps the button 4 times. What number does the label show now?
    let points = 1;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  40. 40.True or false: the app starts up is a load event. (a) True (b) False

Answer key

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

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