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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 286 · 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: the app starts up? (a) a tap event (b) a text event (c) a load event (d) a timer event
  2. 2.👆 What kind of event is this: a countdown hits zero? (a) a load event (b) a timer event (c) a tap event (d) a text event
  3. 3.👆 “On tap → do this” links an event to ___. (a) a font (b) a charger (c) an action (d) a web address
  4. 4.👆 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
  5. 5.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  6. 6.True or false: a countdown hits zero is a load event. (a) False (b) True
  7. 7.👆 A tap handler runs how many times if the user taps 4 times? (a) 4 (b) 0 (c) 8 (d) 1
  8. 8.True or false: the user presses Save is a timer event. (a) False (b) True
  9. 9.👆 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;
    };
  10. 10.👆 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, nameBox.text! (b) Well done, Arjun! (c) Arjun (d) Well done!
  11. 11.👆 The user taps the button 5 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  12. 12.👆 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
  13. 13.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 9;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  14. 14.👆 Code that runs when an event happens is called a ___. (a) header (b) hashtag (c) handler (d) headline
  15. 15.👆 An event in an app is ___. (a) an app store (b) a colour theme (c) something that happens (d) a kind of list
  16. 16.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 5;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  17. 17.👆 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
  18. 18.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  19. 19.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, nameBox.text! (b) Hello! (c) Meera (d) Hello, Meera!
  20. 20.👆 The user types Meera 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! (c) Welcome, Meera! (d) Meera
  21. 21.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  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! (b) Well done, Zoya! (c) Zoya (d) Well done, nameBox.text!
  23. 23.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi, Riya! (b) Riya (c) Hi, nameBox.text! (d) Hi!
  24. 24.👆 What kind of event is this: the user presses Save? (a) a load event (b) a tap event (c) a text event (d) a timer event
  25. 25.True or false: the user types a letter is a text event. (a) True (b) False
  26. 26.👆 What kind of event is this: the user types a letter? (a) a timer event (b) a text event (c) a tap event (d) a load event
  27. 27.👆 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! (b) Riya (c) Well done, nameBox.text! (d) Well done, Riya!
  28. 28.True or false: the user types a letter is a load event. (a) True (b) False
  29. 29.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a tap event (c) a text event (d) a load event
  30. 30.👆 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;
    };
  31. 31.True or false: a finger hits Like is a text event. (a) False (b) True
  32. 32.True or false: the screen first opens is a tap event. (a) False (b) True
  33. 33.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  34. 34.True or false: the app starts up is a text event. (a) True (b) False
  35. 35.True or false: the user presses Save is a tap event. (a) False (b) True
  36. 36.👆 What kind of event is this: a finger hits Like? (a) a text event (b) a timer event (c) a tap event (d) a load event
  37. 37.👆 What kind of event is this: one second passes? (a) a tap event (b) a load event (c) a text event (d) a timer event
  38. 38.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a timer event (c) a load event (d) a text event
  39. 39.👆 Which of these is an event? (a) a list of names (b) the icon colour (c) the font size (d) the user taps a button
  40. 40.👆 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) Zoya (b) Hello, nameBox.text! (c) Hello! (d) Hello, Zoya!

Answer key

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

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