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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 187 · 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 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
  2. 2.👆 What kind of event is this: one second passes? (a) a text event (b) a timer event (c) a load event (d) a tap event
  3. 3.True or false: a finger hits Like is a tap event. (a) True (b) False
  4. 4.👆 The user taps the button 5 times. What number does the label show now?
    let score = 10;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  5. 5.👆 The user taps the button 5 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  6. 6.👆 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;
    };
  7. 7.👆 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) Aman (b) Hello, nameBox.text! (c) Hello, Aman! (d) Hello!
  8. 8.👆 What kind of event is this: a countdown hits zero? (a) a load event (b) a text event (c) a tap event (d) a timer event
  9. 9.👆 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
  10. 10.👆 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
  11. 11.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) a charger (d) an action
  12. 12.👆 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
  13. 13.👆 What kind of event is this: a finger hits Like? (a) a timer event (b) a tap event (c) a load event (d) a text event
  14. 14.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  15. 15.👆 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;
    };
  16. 16.True or false: a 5-minute alarm ends is a timer event. (a) True (b) False
  17. 17.👆 An event in an app is ___. (a) a kind of list (b) an app store (c) a colour theme (d) something that happens
  18. 18.👆 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, Arjun! (b) Arjun (c) Hi! (d) Hi, nameBox.text!
  19. 19.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 1 (c) 8 (d) 4
  20. 20.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  21. 21.👆 The user taps the button 2 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  22. 22.👆 The user taps the button 4 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  23. 23.👆 Code that runs when an event happens is called a ___. (a) handler (b) header (c) headline (d) hashtag
  24. 24.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 1;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  25. 25.👆 The user types Riya 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) Well done, Riya! (c) Well done! (d) Riya
  26. 26.True or false: the app starts up is a load event. (a) False (b) True
  27. 27.👆 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) Well done, nameBox.text! (c) Meera (d) Well done, Meera!
  28. 28.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  29. 29.👆 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) Well done, nameBox.text! (c) Well done! (d) Arjun
  30. 30.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, Zoya! (b) Zoya (c) Hello, nameBox.text! (d) Hello!
  31. 31.👆 The user taps the button 6 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 5;
      label.text = score;
    };
  32. 32.👆 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
  33. 33.👆 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
  34. 34.👆 What kind of event is this: the search box changes? (a) a tap event (b) a load event (c) a text event (d) a timer event
  35. 35.True or false: a countdown hits zero is a timer event. (a) True (b) False
  36. 36.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  37. 37.True or false: a countdown hits zero is a text event. (a) True (b) False
  38. 38.True or false: the search box changes is a load event. (a) False (b) True
  39. 39.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a load event (c) a text event (d) a tap event
  40. 40.True or false: the screen first opens is a timer event. (a) False (b) True

Answer key

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

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