← Events: on tap, do this lesson New set →

App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 214 · 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 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  2. 2.👆 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
  3. 3.👆 A tap handler runs how many times if the user taps 4 times? (a) 8 (b) 1 (c) 4 (d) 0
  4. 4.👆 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
  5. 5.True or false: a finger hits Like is a tap event. (a) False (b) True
  6. 6.True or false: the screen first opens is a load event. (a) False (b) True
  7. 7.👆 What kind of event is this: the screen first opens? (a) a timer event (b) a tap event (c) a load event (d) a text event
  8. 8.👆 Which of these is an event? (a) the font size (b) a list of names (c) the user taps a button (d) the icon colour
  9. 9.👆 “On tap → do this” links an event to ___. (a) a charger (b) a web address (c) an action (d) a font
  10. 10.👆 What kind of event is this: a 5-minute alarm ends? (a) a load event (b) a text event (c) a tap event (d) a timer event
  11. 11.True or false: the search box changes is a text event. (a) False (b) True
  12. 12.👆 What kind of event is this: the app starts up? (a) a text event (b) a tap event (c) a timer event (d) a load event
  13. 13.True or false: a finger hits Like is a timer event. (a) True (b) False
  14. 14.👆 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;
    };
  15. 15.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 3;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  16. 16.👆 What kind of event is this: the search box changes? (a) a text event (b) a timer event (c) a load event (d) a tap event
  17. 17.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  18. 18.👆 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
  19. 19.👆 The user taps the button 2 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  20. 20.👆 What kind of event is this: the user presses Save? (a) a text event (b) a timer event (c) a load event (d) a tap event
  21. 21.True or false: the user taps Play is a timer event. (a) True (b) False
  22. 22.👆 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, nameBox.text! (b) Zoya (c) Well done! (d) Well done, Zoya!
  23. 23.True or false: one second passes is a timer event. (a) False (b) True
  24. 24.👆 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) Riya (c) Well done! (d) Well done, Riya!
  25. 25.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  26. 26.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Kabir (b) Hi! (c) Hi, nameBox.text! (d) Hi, Kabir!
  27. 27.👆 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;
    };
  28. 28.👆 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;
    };
  29. 29.True or false: the user taps Play is a tap event. (a) False (b) True
  30. 30.👆 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
  31. 31.👆 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
  32. 32.True or false: a finger hits Like is a load event. (a) True (b) False
  33. 33.👆 The user taps the button 4 times. What number does the label show now?
    let points = 1;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  34. 34.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  35. 35.👆 The user taps the button 5 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  36. 36.👆 Code that runs when an event happens is called a ___. (a) headline (b) handler (c) header (d) hashtag
  37. 37.👆 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, Meera! (b) Hi! (c) Meera (d) Hi, nameBox.text!
  38. 38.True or false: the user presses Save is a timer event. (a) True (b) False
  39. 39.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 7;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  40. 40.👆 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

Answer key

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

Free app development lessons, practice and worksheets at talentjr.in/app-development-for-students