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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 113 · 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 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
  2. 2.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 7;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  3. 3.👆 The user taps the button 2 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  4. 4.👆 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
  5. 5.👆 “On tap → do this” links an event to ___. (a) a charger (b) a web address (c) an action (d) a font
  6. 6.👆 An event in an app is ___. (a) an app store (b) a kind of list (c) a colour theme (d) something that happens
  7. 7.👆 What kind of event is this: one second passes? (a) a timer event (b) a tap event (c) a text event (d) a load event
  8. 8.True or false: the app starts up is a timer event. (a) True (b) False
  9. 9.👆 What kind of event is this: the user taps Play? (a) a tap event (b) a load event (c) a text event (d) a timer event
  10. 10.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  11. 11.👆 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, nameBox.text! (b) Aman (c) Well done! (d) Well done, Aman!
  12. 12.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  13. 13.👆 A tap handler runs how many times if the user taps 4 times? (a) 4 (b) 8 (c) 1 (d) 0
  14. 14.👆 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;
    };
  15. 15.👆 The user taps the button 1 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 4 times. What number does the label show now?
    let coins = 4;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  17. 17.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 2;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  18. 18.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  19. 19.True or false: one second passes is a timer event. (a) True (b) False
  20. 20.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 10;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  21. 21.👆 The user taps the button 4 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  22. 22.👆 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) Hi, Zoya! (b) Zoya (c) Hi, nameBox.text! (d) Hi!
  23. 23.👆 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) Welcome! (c) Welcome, nameBox.text! (d) Riya
  24. 24.👆 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;
    };
  25. 25.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 8;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  26. 26.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 3;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  27. 27.👆 What kind of event is this: a 5-minute alarm ends? (a) a load event (b) a timer event (c) a text event (d) a tap event
  28. 28.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  29. 29.👆 The user taps the button 4 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  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) ON (b) OFF
  31. 31.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  32. 32.👆 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! (b) Arjun (c) Hello, nameBox.text! (d) Hello, Arjun!
  33. 33.True or false: the user types a letter is a text event. (a) False (b) True
  34. 34.👆 What kind of event is this: the user types a letter? (a) a timer event (b) a text event (c) a load event (d) a tap event
  35. 35.👆 What kind of event is this: the user presses Save? (a) a load event (b) a tap event (c) a timer event (d) a text event
  36. 36.👆 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! (b) Welcome, Kabir! (c) Welcome, nameBox.text! (d) Kabir
  37. 37.👆 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
  38. 38.👆 What kind of event is this: a countdown hits zero? (a) a text event (b) a load event (c) a tap event (d) a timer event
  39. 39.True or false: one second passes is a tap event. (a) False (b) True
  40. 40.👆 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

Answer key

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

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