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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 96 · 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.👆 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) ON (b) OFF
  2. 2.👆 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
  3. 3.👆 The user taps the button 5 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 5;
      label.text = score;
    };
  4. 4.True or false: the user taps Play is a text event. (a) True (b) False
  5. 5.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 9;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  6. 6.👆 What kind of event is this: a countdown hits zero? (a) a load event (b) a tap event (c) a text event (d) a timer event
  7. 7.True or false: the search box changes is a text event. (a) False (b) True
  8. 8.True or false: the screen first opens is a text event. (a) False (b) True
  9. 9.True or false: the app starts up is a load event. (a) False (b) True
  10. 10.👆 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, Kabir! (b) Kabir (c) Welcome, nameBox.text! (d) Welcome!
  11. 11.👆 An event in an app is ___. (a) a kind of list (b) a colour theme (c) an app store (d) something that happens
  12. 12.👆 What kind of event is this: the user types a letter? (a) a text event (b) a timer event (c) a tap event (d) a load event
  13. 13.👆 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
  14. 14.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  15. 15.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  16. 16.👆 The user taps the button 6 times. What number does the label show now?
    let points = 1;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  17. 17.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  18. 18.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  19. 19.True or false: the user taps Play is a tap event. (a) True (b) False
  20. 20.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  21. 21.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello! (b) Zoya (c) Hello, Zoya! (d) Hello, nameBox.text!
  22. 22.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a load event (c) a timer event (d) a text event
  23. 23.👆 A tap handler runs how many times if the user taps 4 times? (a) 1 (b) 4 (c) 0 (d) 8
  24. 24.👆 What kind of event is this: the user taps Play? (a) a text event (b) a load event (c) a timer event (d) a tap event
  25. 25.👆 “On tap → do this” links an event to ___. (a) an action (b) a font (c) a charger (d) a web address
  26. 26.👆 What kind of event is this: the user presses Save? (a) a text event (b) a load event (c) a timer event (d) a tap event
  27. 27.👆 The user types Aman 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! (b) Aman (c) Well done, nameBox.text! (d) Well done, Aman!
  28. 28.👆 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) ON (b) OFF
  29. 29.👆 The user taps the button 5 times. What number does the label show now?
    let score = 2;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  30. 30.👆 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) Riya (b) Welcome! (c) Welcome, nameBox.text! (d) Welcome, Riya!
  31. 31.👆 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) ON (b) OFF
  32. 32.👆 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
  33. 33.👆 What kind of event is this: the app starts up? (a) a tap event (b) a timer event (c) a text event (d) a load event
  34. 34.👆 Which of these is an event? (a) the font size (b) a list of names (c) the user taps a button (d) the icon colour
  35. 35.👆 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) Kabir (b) Hello! (c) Hello, nameBox.text! (d) Hello, Kabir!
  36. 36.👆 What kind of event is this: a finger hits Like? (a) a tap event (b) a text event (c) a timer event (d) a load event
  37. 37.👆 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) OFF (b) ON
  38. 38.👆 What kind of event is this: the search box changes? (a) a load event (b) a text event (c) a timer event (d) a tap event
  39. 39.True or false: the user taps Play is a timer event. (a) False (b) True
  40. 40.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };

Answer key

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

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