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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 116 · 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 search box changes is a text event. (a) True (b) False
  2. 2.True or false: a finger hits Like is a timer event. (a) False (b) True
  3. 3.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 9;
    button.onTap = function () {
      stars = stars + 1;
      label.text = stars;
    };
  4. 4.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 5;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  5. 5.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  6. 6.👆 What kind of event is this: the app starts up? (a) a text event (b) a tap event (c) a load event (d) a timer event
  7. 7.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  8. 8.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  9. 9.👆 What kind of event is this: a countdown hits zero? (a) a timer event (b) a load event (c) a tap event (d) a text event
  10. 10.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) an action (d) a charger
  11. 11.👆 What kind of event is this: the screen first opens? (a) a load event (b) a text event (c) a tap event (d) a timer event
  12. 12.True or false: a 5-minute alarm ends is a text event. (a) False (b) True
  13. 13.👆 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
  14. 14.👆 The user taps the button 4 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  15. 15.👆 Code that runs when an event happens is called a ___. (a) header (b) headline (c) hashtag (d) handler
  16. 16.True or false: the app starts up is a tap event. (a) False (b) True
  17. 17.👆 What kind of event is this: a finger hits Like? (a) a load event (b) a text event (c) a timer event (d) a tap event
  18. 18.👆 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
  19. 19.👆 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) Arjun (b) Well done, nameBox.text! (c) Well done! (d) Well done, Arjun!
  20. 20.👆 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) ON (b) OFF
  21. 21.👆 The user taps the button 5 times. What number does the label show now?
    let points = 3;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  22. 22.👆 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
  23. 23.True or false: a countdown hits zero is a timer event. (a) False (b) True
  24. 24.👆 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) ON (b) OFF
  25. 25.👆 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;
    };
  26. 26.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  27. 27.👆 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;
    };
  28. 28.👆 What kind of event is this: a 5-minute alarm ends? (a) a text event (b) a tap event (c) a timer event (d) a load event
  29. 29.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 1;
      label.text = stars;
    };
  30. 30.👆 The user taps the button 3 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  31. 31.👆 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) Hello, Riya! (b) Hello, nameBox.text! (c) Hello! (d) Riya
  32. 32.👆 The user taps the button 4 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  33. 33.True or false: a finger hits Like is a tap event. (a) False (b) True
  34. 34.👆 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
  35. 35.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  36. 36.👆 The user taps the button 4 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  37. 37.👆 The user taps the button 5 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  38. 38.True or false: the user types a letter is a timer event. (a) True (b) False
  39. 39.True or false: the user types a letter is a text event. (a) False (b) True
  40. 40.👆 Which of these is an event? (a) a list of names (b) the font size (c) the user taps a button (d) the icon colour

Answer key

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

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