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

App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 178 · 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.👆 A tap handler runs how many times if the user taps 4 times? (a) 8 (b) 4 (c) 1 (d) 0
  2. 2.👆 The user taps the button 3 times. What number does the label show now?
    let score = 5;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  3. 3.True or false: a countdown hits zero is a tap event. (a) True (b) False
  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) ON (b) OFF
  5. 5.👆 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
  6. 6.👆 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! (c) Riya (d) Well done, Riya!
  7. 7.👆 What kind of event is this: the user presses Save? (a) a text event (b) a load event (c) a timer event (d) a tap event
  8. 8.👆 What kind of event is this: the user taps Play? (a) a load event (b) a text event (c) a tap event (d) a timer event
  9. 9.👆 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
  10. 10.True or false: the app starts up is a load event. (a) False (b) True
  11. 11.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  12. 12.👆 “On tap → do this” links an event to ___. (a) a web address (b) a font (c) a charger (d) an action
  13. 13.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  14. 14.👆 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;
    };
  15. 15.👆 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) Hello, nameBox.text! (c) Hello! (d) Zoya
  16. 16.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a timer event (c) a text event (d) a load event
  17. 17.True or false: the user presses Save is a tap event. (a) False (b) True
  18. 18.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome! (b) Riya (c) Welcome, Riya! (d) Welcome, nameBox.text!
  19. 19.True or false: the user presses Save is a text event. (a) False (b) True
  20. 20.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  21. 21.👆 An event in an app is ___. (a) something that happens (b) a colour theme (c) a kind of list (d) an app store
  22. 22.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 2;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  23. 23.👆 The user taps the button 2 times. What number does the label show now?
    let points = 2;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  24. 24.👆 Code that runs when an event happens is called a ___. (a) header (b) headline (c) handler (d) hashtag
  25. 25.👆 Which of these is an event? (a) a list of names (b) the user taps a button (c) the font size (d) the icon colour
  26. 26.👆 What kind of event is this: a finger hits Like? (a) a text event (b) a load event (c) a timer event (d) a tap event
  27. 27.👆 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;
    };
  28. 28.👆 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;
    };
  29. 29.👆 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, Kabir! (b) Hello, nameBox.text! (c) Hello! (d) Kabir
  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 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, nameBox.text! (b) Arjun (c) Hi, Arjun! (d) Hi!
  32. 32.👆 What kind of event is this: the screen first opens? (a) a text event (b) a timer event (c) a tap event (d) a load event
  33. 33.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Aman (b) Hi! (c) Hi, nameBox.text! (d) Hi, Aman!
  34. 34.👆 The user taps the button 8 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.True or false: the user types a letter is a tap event. (a) True (b) False
  36. 36.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 2;
    button.onTap = function () {
      stars = stars + 2;
      label.text = stars;
    };
  37. 37.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  38. 38.True or false: the screen first opens is a text event. (a) True (b) False
  39. 39.👆 What kind of event is this: the app starts up? (a) a timer event (b) a tap event (c) a load event (d) a text event
  40. 40.True or false: the screen first opens is a timer event. (a) False (b) True

Answer key

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

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