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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 114 · 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 search box changes? (a) a timer event (b) a text event (c) a tap event (d) a load event
  2. 2.👆 What kind of event is this: a 5-minute alarm ends? (a) a load event (b) a timer event (c) a tap event (d) a text event
  3. 3.👆 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) Zoya (b) Welcome, Zoya! (c) Welcome! (d) Welcome, nameBox.text!
  4. 4.👆 What kind of event is this: the app starts up? (a) a tap event (b) a timer event (c) a load event (d) a text event
  5. 5.👆 An event in an app is ___. (a) an app store (b) something that happens (c) a kind of list (d) a colour theme
  6. 6.👆 A tap handler runs how many times if the user taps 4 times? (a) 1 (b) 4 (c) 8 (d) 0
  7. 7.👆 What kind of event is this: a countdown hits zero? (a) a timer event (b) a tap event (c) a text event (d) a load event
  8. 8.True or false: the app starts up is a timer event. (a) True (b) False
  9. 9.👆 What kind of event is this: the screen first opens? (a) a text event (b) a timer event (c) a load event (d) a tap event
  10. 10.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 9;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  11. 11.👆 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
  12. 12.👆 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
  13. 13.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 3;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  14. 14.👆 Which of these is an event? (a) the user taps a button (b) a list of names (c) the font size (d) the icon colour
  15. 15.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  16. 16.👆 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) OFF (b) ON
  17. 17.👆 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) Arjun (b) Hi, nameBox.text! (c) Hi, Arjun! (d) Hi!
  18. 18.👆 The user taps the button 4 times. What number does the label show now?
    let score = 2;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  19. 19.👆 Code that runs when an event happens is called a ___. (a) headline (b) hashtag (c) header (d) handler
  20. 20.👆 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;
    };
  21. 21.True or false: a countdown hits zero is a text event. (a) True (b) False
  22. 22.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Riya (b) Welcome, Riya! (c) Welcome! (d) Welcome, nameBox.text!
  23. 23.True or false: a 5-minute alarm ends is a timer event. (a) True (b) False
  24. 24.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  25. 25.👆 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;
    };
  26. 26.True or false: a 5-minute alarm ends is a load event. (a) False (b) True
  27. 27.👆 What kind of event is this: the user taps Play? (a) a load event (b) a timer event (c) a tap event (d) a text event
  28. 28.👆 “On tap → do this” links an event to ___. (a) a charger (b) a font (c) a web address (d) an action
  29. 29.👆 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, nameBox.text! (b) Well done! (c) Meera (d) Well done, Meera!
  30. 30.👆 The user taps the button 4 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  31. 31.👆 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) OFF (b) ON
  32. 32.👆 The user taps the button 2 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  33. 33.👆 The user taps the button 6 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  34. 34.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  35. 35.👆 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;
    };
  36. 36.True or false: a countdown hits zero is a load event. (a) True (b) False
  37. 37.👆 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
  38. 38.True or false: the screen first opens is a timer event. (a) False (b) True
  39. 39.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 1;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  40. 40.True or false: one second passes is a tap event. (a) True (b) False

Answer key

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

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