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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 213 · 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 types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, Aman! (b) Hello, nameBox.text! (c) Hello! (d) Aman
  2. 2.👆 Which of these is an event? (a) the user taps a button (b) the icon colour (c) a list of names (d) the font size
  3. 3.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 6;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  4. 4.True or false: a countdown hits zero is a tap event. (a) False (b) True
  5. 5.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  6. 6.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  7. 7.👆 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) Zoya (c) Hello, nameBox.text! (d) Hello!
  8. 8.👆 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;
    };
  9. 9.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  10. 10.👆 The user taps the button 2 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  11. 11.👆 The user taps the button 3 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  12. 12.👆 The user taps the button 2 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  13. 13.👆 The user taps the button 3 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  14. 14.👆 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
  15. 15.👆 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
  16. 16.👆 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, Arjun! (b) Hi! (c) Hi, nameBox.text! (d) Arjun
  17. 17.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  18. 18.👆 Code that runs when an event happens is called a ___. (a) headline (b) header (c) handler (d) hashtag
  19. 19.True or false: a countdown hits zero is a timer event. (a) False (b) True
  20. 20.True or false: the user presses Save is a tap event. (a) True (b) False
  21. 21.👆 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!
  22. 22.👆 An event in an app is ___. (a) an app store (b) a colour theme (c) something that happens (d) a kind of list
  23. 23.👆 “On tap → do this” links an event to ___. (a) a font (b) an action (c) a web address (d) a charger
  24. 24.True or false: the user presses Save is a load event. (a) True (b) False
  25. 25.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 8;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  26. 26.True or false: the search box changes is a timer event. (a) False (b) True
  27. 27.👆 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;
    };
  28. 28.👆 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, nameBox.text! (b) Hi, Meera! (c) Meera (d) Hi!
  29. 29.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  30. 30.👆 The user taps the button 2 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  31. 31.👆 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;
    };
  32. 32.👆 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
  33. 33.👆 The user types Meera 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, Meera! (c) Well done, nameBox.text! (d) Meera
  34. 34.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 9;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  35. 35.True or false: the app starts up is a load event. (a) True (b) False
  36. 36.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 7;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  37. 37.👆 The user types Aman 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, Aman! (c) Aman (d) Well done!
  38. 38.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 8;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  39. 39.True or false: the user taps Play is a tap event. (a) False (b) True
  40. 40.👆 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) OFF (b) ON

Answer key

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

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