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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 312 · 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.True or false: the app starts up is a tap event. (a) False (b) True
  2. 2.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 1;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  3. 3.True or false: the user types a letter is a text event. (a) False (b) True
  4. 4.True or false: a countdown hits zero is a timer event. (a) False (b) True
  5. 5.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 6;
    button.onTap = function () {
      lives = lives + 4;
      label.text = lives;
    };
  6. 6.True or false: the app starts up is a load event. (a) False (b) True
  7. 7.👆 What kind of event is this: a finger hits Like? (a) a load event (b) a timer event (c) a tap event (d) a text event
  8. 8.True or false: one second passes is a text event. (a) False (b) True
  9. 9.👆 What kind of event is this: a countdown hits zero? (a) a timer event (b) a tap event (c) a load event (d) a text event
  10. 10.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 10;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  11. 11.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) header (c) headline (d) handler
  12. 12.👆 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;
    };
  13. 13.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  14. 14.👆 What kind of event is this: the app starts up? (a) a tap event (b) a load event (c) a timer event (d) a text event
  15. 15.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 10;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  16. 16.👆 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;
    };
  17. 17.👆 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
  18. 18.👆 The user taps the button 4 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 3 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  20. 20.👆 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! (c) Hi, Meera! (d) Meera
  21. 21.👆 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
  22. 22.👆 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, Aman! (b) Well done! (c) Aman (d) Well done, nameBox.text!
  23. 23.👆 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
  24. 24.👆 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
  25. 25.👆 What kind of event is this: the user types a letter? (a) a tap event (b) a timer event (c) a text event (d) a load event
  26. 26.👆 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;
    };
  27. 27.👆 An event in an app is ___. (a) an app store (b) something that happens (c) a kind of list (d) a colour theme
  28. 28.True or false: a 5-minute alarm ends is a timer event. (a) False (b) True
  29. 29.True or false: the user taps Play is a tap event. (a) False (b) True
  30. 30.👆 What kind of event is this: one second passes? (a) a text event (b) a tap event (c) a timer event (d) a load event
  31. 31.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  32. 32.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  33. 33.👆 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;
    };
  34. 34.👆 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;
    };
  35. 35.👆 What kind of event is this: a 5-minute alarm ends? (a) a timer event (b) a tap event (c) a text event (d) a load event
  36. 36.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  37. 37.👆 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) Arjun (b) Well done! (c) Well done, Arjun! (d) Well done, nameBox.text!
  38. 38.👆 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;
    };
  39. 39.👆 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
  40. 40.True or false: a finger hits Like is a tap event. (a) True (b) False

Answer key

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

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