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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 294 · 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: a 5-minute alarm ends? (a) a tap event (b) a text event (c) a load event (d) a timer event
  2. 2.👆 The user taps the button 6 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
  3. 3.👆 What kind of event is this: the app starts up? (a) a text event (b) a timer event (c) a tap event (d) a load event
  4. 4.👆 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) Riya (b) Hi! (c) Hi, Riya! (d) Hi, nameBox.text!
  5. 5.👆 The user types Arjun 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) Arjun (c) Well done! (d) Well done, Arjun!
  6. 6.👆 The user types Kabir 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) Welcome, Kabir! (d) Kabir
  7. 7.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 5;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  8. 8.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 4;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  9. 9.👆 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
  10. 10.👆 What kind of event is this: the search box changes? (a) a load event (b) a text event (c) a tap event (d) a timer event
  11. 11.👆 “On tap → do this” links an event to ___. (a) a web address (b) a charger (c) a font (d) an action
  12. 12.👆 What kind of event is this: one second passes? (a) a tap event (b) a load event (c) a timer event (d) a text event
  13. 13.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 10;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  14. 14.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a text event (c) a load event (d) a timer event
  15. 15.👆 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;
    };
  16. 16.👆 The user types Riya 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, Riya! (c) Well done! (d) Riya
  17. 17.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Meera (b) Hi, nameBox.text! (c) Hi, Meera! (d) Hi!
  18. 18.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  19. 19.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  20. 20.👆 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, Meera! (b) Well done! (c) Well done, nameBox.text! (d) Meera
  21. 21.👆 The user taps the button 7 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
  22. 22.👆 What kind of event is this: the user presses Save? (a) a text event (b) a load event (c) a tap event (d) a timer event
  23. 23.True or false: one second passes is a timer event. (a) False (b) True
  24. 24.👆 The user taps the button 3 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  25. 25.True or false: a finger hits Like is a tap event. (a) True (b) False
  26. 26.True or false: the user taps Play is a load event. (a) False (b) True
  27. 27.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 1;
      label.text = stars;
    };
  28. 28.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  29. 29.👆 Which of these is an event? (a) the icon colour (b) the font size (c) a list of names (d) the user taps a button
  30. 30.👆 The user taps the button 1 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
  31. 31.👆 A tap handler runs how many times if the user taps 4 times? (a) 8 (b) 4 (c) 0 (d) 1
  32. 32.👆 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
  33. 33.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  34. 34.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  35. 35.True or false: one second passes is a load event. (a) True (b) False
  36. 36.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Riya (b) Hello! (c) Hello, nameBox.text! (d) Hello, Riya!
  37. 37.👆 The user taps the button 2 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  38. 38.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 10;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  39. 39.👆 Code that runs when an event happens is called a ___. (a) handler (b) header (c) headline (d) hashtag
  40. 40.👆 The user taps the button 6 times. What number does the label show now?
    let stars = 5;
    button.onTap = function () {
      stars = stars + 2;
      label.text = stars;
    };

Answer key

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

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