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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 100 · 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 app starts up? (a) a timer event (b) a tap event (c) a text event (d) a load event
  2. 2.👆 “On tap → do this” links an event to ___. (a) a charger (b) an action (c) a font (d) a web address
  3. 3.👆 The user taps the button 4 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  4. 4.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  5. 5.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  6. 6.True or false: the user types a letter is a load event. (a) False (b) True
  7. 7.True or false: a 5-minute alarm ends is a tap event. (a) True (b) False
  8. 8.👆 The user taps the button 4 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  9. 9.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  10. 10.True or false: the user taps Play is a tap event. (a) False (b) True
  11. 11.👆 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, nameBox.text! (c) Welcome, Riya! (d) Welcome!
  12. 12.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome! (b) Welcome, Meera! (c) Meera (d) Welcome, nameBox.text!
  13. 13.👆 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
  14. 14.👆 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
  15. 15.👆 Which of these is an event? (a) the user taps a button (b) a list of names (c) the font size (d) the icon colour
  16. 16.👆 The user taps the button 3 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 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
  18. 18.👆 An event in an app is ___. (a) a colour theme (b) something that happens (c) an app store (d) a kind of list
  19. 19.👆 The user taps the button 5 times. What number does the label show now?
    let points = 2;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  20. 20.👆 What kind of event is this: a countdown hits zero? (a) a text event (b) a tap event (c) a timer event (d) a load event
  21. 21.True or false: a 5-minute alarm ends is a timer event. (a) True (b) False
  22. 22.True or false: the user presses Save is a timer event. (a) False (b) True
  23. 23.👆 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) Well done, nameBox.text! (c) Aman (d) Well done, Aman!
  24. 24.True or false: the search box changes is a load event. (a) True (b) False
  25. 25.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome! (b) Welcome, Aman! (c) Welcome, nameBox.text! (d) Aman
  26. 26.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) header (c) headline (d) handler
  27. 27.👆 The user taps the button 2 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  28. 28.True or false: the app starts up is a load event. (a) False (b) True
  29. 29.👆 What kind of event is this: the user presses Save? (a) a text event (b) a timer event (c) a load event (d) a tap event
  30. 30.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 2;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };
  31. 31.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 8;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  32. 32.True or false: one second passes is a timer event. (a) True (b) False
  33. 33.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  34. 34.👆 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
  35. 35.👆 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! (b) Aman (c) Hi, Aman! (d) Hi, nameBox.text!
  36. 36.True or false: the user taps Play is a text event. (a) False (b) True
  37. 37.👆 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, nameBox.text! (c) Arjun (d) Well done, Arjun!
  38. 38.👆 The user taps the button 3 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  39. 39.True or false: a finger hits Like is a tap event. (a) True (b) False
  40. 40.True or false: a 5-minute alarm ends is a text event. (a) False (b) True

Answer key

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

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