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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 87 · 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 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) ON (b) OFF
  2. 2.True or false: the app starts up is a load event. (a) False (b) True
  3. 3.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 3;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  4. 4.👆 Which of these is an event? (a) the font size (b) a list of names (c) the icon colour (d) the user taps a button
  5. 5.👆 The user taps the button 6 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 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
  7. 7.👆 The user taps the button 6 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  8. 8.👆 A tap handler runs how many times if the user taps 4 times? (a) 1 (b) 4 (c) 0 (d) 8
  9. 9.👆 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;
    };
  10. 10.👆 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
  11. 11.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  12. 12.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  13. 13.👆 The user taps the button 6 times. What number does the label show now?
    let lives = 3;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  14. 14.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome! (b) Welcome, Zoya! (c) Zoya (d) Welcome, nameBox.text!
  15. 15.True or false: the user presses Save is a load event. (a) True (b) False
  16. 16.👆 What kind of event is this: the user taps Play? (a) a load event (b) a timer event (c) a text event (d) a tap event
  17. 17.True or false: one second passes is a tap event. (a) True (b) False
  18. 18.👆 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
  19. 19.👆 What kind of event is this: a countdown hits zero? (a) a text event (b) a timer event (c) a load event (d) a tap event
  20. 20.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  21. 21.👆 “On tap → do this” links an event to ___. (a) a web address (b) a font (c) an action (d) a charger
  22. 22.👆 What kind of event is this: the app starts up? (a) a text event (b) a load event (c) a timer event (d) a tap event
  23. 23.👆 What kind of event is this: a 5-minute alarm ends? (a) a timer event (b) a load event (c) a tap event (d) a text event
  24. 24.👆 Code that runs when an event happens is called a ___. (a) header (b) headline (c) handler (d) hashtag
  25. 25.👆 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;
    };
  26. 26.True or false: the user taps Play is a timer event. (a) True (b) False
  27. 27.True or false: the user types a letter is a tap event. (a) False (b) True
  28. 28.True or false: the user taps Play is a tap event. (a) True (b) False
  29. 29.👆 An event in an app is ___. (a) something that happens (b) a colour theme (c) an app store (d) a kind of list
  30. 30.True or false: the screen first opens is a load event. (a) False (b) True
  31. 31.👆 What kind of event is this: the screen first opens? (a) a timer event (b) a tap event (c) a load event (d) a text event
  32. 32.👆 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) OFF (b) ON
  33. 33.👆 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;
    };
  34. 34.👆 The user types Kabir 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, Kabir! (b) Well done! (c) Well done, nameBox.text! (d) Kabir
  35. 35.👆 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;
    };
  36. 36.True or false: the search box changes is a text event. (a) True (b) False
  37. 37.👆 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
  38. 38.👆 The user taps the button 3 times. What number does the label show now?
    let score = 10;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  39. 39.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 9;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  40. 40.👆 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

Answer key

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

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