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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 72 · 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 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
  2. 2.👆 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, Arjun! (b) Arjun (c) Well done, nameBox.text! (d) Well done!
  3. 3.👆 What kind of event is this: the user presses Save? (a) a text event (b) a tap event (c) a load event (d) a timer event
  4. 4.👆 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;
    };
  5. 5.👆 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
  6. 6.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 8 (c) 1 (d) 4
  7. 7.👆 The user taps the button 5 times. What number does the label show now?
    let points = 3;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  8. 8.👆 “On tap → do this” links an event to ___. (a) a web address (b) a charger (c) a font (d) an action
  9. 9.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 9;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  10. 10.👆 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, nameBox.text! (b) Aman (c) Welcome! (d) Welcome, Aman!
  11. 11.True or false: the user taps Play is a timer event. (a) True (b) False
  12. 12.👆 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
  13. 13.👆 What kind of event is this: the search box changes? (a) a text event (b) a tap event (c) a timer event (d) a load event
  14. 14.👆 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
  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.True or false: one second passes is a tap event. (a) False (b) True
  17. 17.👆 The user types Kabir 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) Kabir (c) Well done, nameBox.text! (d) Well done, Kabir!
  18. 18.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  19. 19.👆 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
  20. 20.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Zoya (b) Hi, nameBox.text! (c) Hi! (d) Hi, Zoya!
  21. 21.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 3;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };
  22. 22.👆 The user taps the button 2 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  23. 23.👆 An event in an app is ___. (a) a kind of list (b) something that happens (c) a colour theme (d) an app store
  24. 24.👆 What kind of event is this: the user types a letter? (a) a load event (b) a timer event (c) a tap event (d) a text event
  25. 25.👆 Which of these is an event? (a) the icon colour (b) the user taps a button (c) a list of names (d) the font size
  26. 26.👆 Code that runs when an event happens is called a ___. (a) handler (b) headline (c) header (d) hashtag
  27. 27.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  28. 28.👆 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) Welcome, Riya! (b) Riya (c) Welcome, nameBox.text! (d) Welcome!
  29. 29.👆 The user taps the button 4 times. What number does the label show now?
    let score = 10;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  30. 30.👆 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
  31. 31.True or false: a 5-minute alarm ends is a timer event. (a) False (b) True
  32. 32.👆 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;
    };
  33. 33.👆 The user taps the button 6 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  34. 34.True or false: a countdown hits zero is a timer event. (a) False (b) True
  35. 35.👆 What kind of event is this: one second passes? (a) a load event (b) a timer event (c) a text event (d) a tap event
  36. 36.👆 The user taps the button 4 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  37. 37.👆 The user taps the button 6 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  38. 38.True or false: a 5-minute alarm ends is a text event. (a) False (b) True
  39. 39.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a tap event (c) a text event (d) a load event
  40. 40.True or false: a finger hits Like is a tap event. (a) False (b) True

Answer key

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

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