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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 233 · 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.👆 Which of these is an event? (a) the font size (b) the user taps a button (c) the icon colour (d) a list of names
  2. 2.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 4 (c) 1 (d) 8
  3. 3.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 6;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  4. 4.👆 What kind of event is this: the user presses Save? (a) a text event (b) a timer event (c) a tap event (d) a load event
  5. 5.👆 The user types Arjun 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, nameBox.text! (c) Welcome, Arjun! (d) Arjun
  6. 6.👆 What kind of event is this: the app starts up? (a) a timer event (b) a load event (c) a text event (d) a tap event
  7. 7.👆 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, Kabir! (c) Well done, nameBox.text! (d) Well done!
  8. 8.👆 “On tap → do this” links an event to ___. (a) a charger (b) an action (c) a web address (d) a font
  9. 9.👆 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! (c) Well done, nameBox.text! (d) Arjun
  10. 10.👆 The user taps the button 3 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  11. 11.True or false: the screen first opens is a timer event. (a) True (b) False
  12. 12.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a timer event (c) a load event (d) a text event
  13. 13.True or false: a 5-minute alarm ends is a timer event. (a) True (b) False
  14. 14.👆 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) Riya (b) Well done, Riya! (c) Well done! (d) Well done, nameBox.text!
  15. 15.True or false: the app starts up is a load event. (a) False (b) True
  16. 16.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) headline (c) header (d) handler
  17. 17.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  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) ON (b) OFF
  19. 19.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  20. 20.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 10;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  21. 21.True or false: the user presses Save is a text event. (a) True (b) False
  22. 22.👆 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
  23. 23.👆 What kind of event is this: the user types a letter? (a) a load event (b) a timer event (c) a text event (d) a tap event
  24. 24.👆 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) Zoya (b) Hi! (c) Hi, Zoya! (d) Hi, nameBox.text!
  25. 25.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 10;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  26. 26.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 2;
      label.text = stars;
    };
  27. 27.True or false: one second passes is a timer event. (a) False (b) True
  28. 28.👆 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
  29. 29.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  30. 30.👆 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
  31. 31.👆 The user taps the button 5 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 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
  33. 33.True or false: a 5-minute alarm ends is a load event. (a) False (b) True
  34. 34.👆 The user taps the button 2 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  35. 35.👆 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;
    };
  36. 36.👆 The user taps the button 2 times. What number does the label show now?
    let score = 2;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  37. 37.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome, nameBox.text! (b) Welcome, Aman! (c) Welcome! (d) Aman
  38. 38.👆 The user taps the button 3 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  39. 39.👆 What kind of event is this: the search box changes? (a) a load event (b) a text event (c) a timer event (d) a tap event
  40. 40.👆 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

Answer key

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

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