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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 119 · 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: a countdown hits zero? (a) a text event (b) a tap event (c) a timer event (d) a load event
  2. 2.👆 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;
    };
  3. 3.True or false: the search box changes is a tap event. (a) True (b) False
  4. 4.True or false: the user presses Save is a tap event. (a) False (b) True
  5. 5.👆 An event in an app is ___. (a) a kind of list (b) an app store (c) something that happens (d) a colour theme
  6. 6.👆 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
  7. 7.True or false: a 5-minute alarm ends is a timer event. (a) False (b) True
  8. 8.👆 A tap handler runs how many times if the user taps 4 times? (a) 1 (b) 8 (c) 0 (d) 4
  9. 9.👆 Code that runs when an event happens is called a ___. (a) header (b) hashtag (c) headline (d) handler
  10. 10.True or false: the user types a letter is a text event. (a) False (b) True
  11. 11.👆 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
  12. 12.👆 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
  13. 13.👆 What kind of event is this: the app starts up? (a) a timer event (b) a text event (c) a tap event (d) a load event
  14. 14.👆 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
  15. 15.👆 “On tap → do this” links an event to ___. (a) a font (b) an action (c) a charger (d) a web address
  16. 16.👆 The user taps the button 4 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  17. 17.👆 The user types Zoya 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, Zoya! (b) Well done! (c) Well done, nameBox.text! (d) Zoya
  18. 18.👆 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
  19. 19.👆 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
  20. 20.👆 The user taps the button 2 times. What number does the label show now?
    let points = 1;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  21. 21.👆 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;
    };
  22. 22.👆 The user taps the button 3 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  23. 23.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  24. 24.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  25. 25.👆 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;
    };
  26. 26.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a text event (c) a load event (d) a timer event
  27. 27.👆 The user taps the button 3 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  28. 28.True or false: a finger hits Like is a tap event. (a) False (b) True
  29. 29.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  30. 30.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a text event (c) a load event (d) a timer event
  31. 31.True or false: the screen first opens is a load event. (a) True (b) False
  32. 32.True or false: the user presses Save is a timer event. (a) False (b) True
  33. 33.True or false: the app starts up is a text event. (a) True (b) False
  34. 34.👆 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;
    };
  35. 35.👆 Which of these is an event? (a) the font size (b) a list of names (c) the icon colour (d) the user taps a button
  36. 36.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello! (b) Hello, nameBox.text! (c) Hello, Kabir! (d) Kabir
  37. 37.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 5;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };
  38. 38.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  39. 39.👆 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, Kabir! (b) Kabir (c) Well done, nameBox.text! (d) Well done!
  40. 40.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };

Answer key

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

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