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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 298 · 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 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
  2. 2.👆 Which of these is an event? (a) a list of names (b) the icon colour (c) the font size (d) the user taps a button
  3. 3.👆 The user taps the button 2 times. What number does the label show now?
    let points = 3;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  4. 4.👆 An event in an app is ___. (a) a colour theme (b) an app store (c) something that happens (d) a kind of list
  5. 5.👆 The user taps the button 4 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 5;
      label.text = score;
    };
  6. 6.👆 What kind of event is this: the search box changes? (a) a text event (b) a timer event (c) a tap event (d) a load event
  7. 7.👆 The user taps the button 6 times. What number does the label show now?
    let points = 3;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  8. 8.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Well done, " + nameBox.text + "!";
    };     (a) Zoya (b) Well done, Zoya! (c) Well done! (d) Well done, nameBox.text!
  9. 9.👆 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) OFF (b) ON
  10. 10.👆 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, Arjun! (b) Hello, nameBox.text! (c) Arjun (d) Hello!
  11. 11.👆 The user types Arjun 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) Hi, Arjun! (c) Hi! (d) Arjun
  12. 12.True or false: the app starts up is a tap event. (a) True (b) False
  13. 13.True or false: a countdown hits zero is a load event. (a) True (b) False
  14. 14.True or false: the search box changes is a text event. (a) False (b) True
  15. 15.👆 A tap handler runs how many times if the user taps 4 times? (a) 4 (b) 1 (c) 0 (d) 8
  16. 16.👆 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) ON (b) OFF
  17. 17.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 7;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  18. 18.👆 The user taps the button 4 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  19. 19.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a tap event (c) a load event (d) a text event
  20. 20.👆 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) ON (b) OFF
  21. 21.👆 What kind of event is this: a finger hits Like? (a) a load event (b) a text event (c) a tap event (d) a timer event
  22. 22.True or false: one second passes is a timer event. (a) True (b) False
  23. 23.True or false: a countdown hits zero is a timer event. (a) True (b) False
  24. 24.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  25. 25.👆 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! (b) Well done, Arjun! (c) Well done, nameBox.text! (d) Arjun
  26. 26.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  27. 27.👆 What kind of event is this: the user types a letter? (a) a tap event (b) a load event (c) a timer event (d) a text event
  28. 28.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 0;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  29. 29.👆 “On tap → do this” links an event to ___. (a) a font (b) a charger (c) a web address (d) an action
  30. 30.True or false: a countdown hits zero is a text event. (a) False (b) True
  31. 31.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi, Aman! (b) Hi, nameBox.text! (c) Hi! (d) Aman
  32. 32.👆 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) Hello! (c) Aman (d) Hello, Aman!
  33. 33.👆 The user taps the button 6 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.True or false: one second passes is a tap event. (a) False (b) True
  35. 35.👆 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) Kabir (b) Welcome, Kabir! (c) Welcome, nameBox.text! (d) Welcome!
  36. 36.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  37. 37.👆 What kind of event is this: the app starts up? (a) a load event (b) a text event (c) a timer event (d) a tap event
  38. 38.True or false: the user presses Save is a tap event. (a) False (b) True
  39. 39.True or false: a finger hits Like is a tap event. (a) True (b) False
  40. 40.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };

Answer key

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

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