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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 239 · 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 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
  2. 2.True or false: a 5-minute alarm ends is a tap event. (a) True (b) False
  3. 3.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a text event (c) a load event (d) a timer event
  4. 4.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  5. 5.👆 The user taps the button 5 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 5;
      label.text = score;
    };
  6. 6.👆 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
  7. 7.👆 The user taps the button 3 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  8. 8.👆 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
  9. 9.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 4;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  10. 10.👆 Which of these is an event? (a) the icon colour (b) a list of names (c) the font size (d) the user taps a button
  11. 11.👆 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
  12. 12.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  13. 13.👆 What kind of event is this: the search box changes? (a) a text event (b) a timer event (c) a tap event (d) a load event
  14. 14.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  15. 15.True or false: one second passes is a text event. (a) True (b) False
  16. 16.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) header (c) headline (d) handler
  17. 17.👆 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! (b) Riya (c) Hi, Riya! (d) Hi, nameBox.text!
  18. 18.👆 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;
    };
  19. 19.👆 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;
    };
  20. 20.👆 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
  21. 21.True or false: a 5-minute alarm ends is a timer event. (a) False (b) True
  22. 22.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 3;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  23. 23.True or false: the search box changes is a text event. (a) False (b) True
  24. 24.True or false: one second passes is a timer event. (a) False (b) True
  25. 25.👆 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;
    };
  26. 26.True or false: the user taps Play is a tap event. (a) True (b) False
  27. 27.👆 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
  28. 28.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 0;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };
  29. 29.👆 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;
    };
  30. 30.👆 The user taps the button 5 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  31. 31.👆 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) Kabir (b) Hello, Kabir! (c) Hello! (d) Hello, nameBox.text!
  32. 32.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  33. 33.True or false: a countdown hits zero is a timer event. (a) False (b) True
  34. 34.👆 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) Meera (c) Hi, nameBox.text! (d) Hi!
  35. 35.True or false: the app starts up is a load event. (a) False (b) True
  36. 36.True or false: the screen first opens is a tap event. (a) True (b) False
  37. 37.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  38. 38.👆 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
  39. 39.👆 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, Kabir! (c) Hi! (d) Hi, nameBox.text!
  40. 40.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };

Answer key

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

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