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App Dev Worksheet: Events

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

Answer key

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

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