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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 244 · 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 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  2. 2.👆 The user taps the button 5 times. What number does the label show now?
    let score = 10;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  3. 3.👆 An event in an app is ___. (a) something that happens (b) an app store (c) a colour theme (d) a kind of list
  4. 4.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 3;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  5. 5.True or false: the user types a letter is a tap event. (a) True (b) False
  6. 6.👆 What kind of event is this: the search box changes? (a) a load event (b) a timer event (c) a tap event (d) a text event
  7. 7.👆 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;
    };
  8. 8.👆 The user types Arjun in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome, Arjun! (b) Welcome! (c) Welcome, nameBox.text! (d) Arjun
  9. 9.True or false: the user taps Play is a timer event. (a) False (b) True
  10. 10.👆 The user taps the button 2 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  11. 11.True or false: a countdown hits zero is a load event. (a) False (b) True
  12. 12.👆 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;
    };
  13. 13.True or false: a finger hits Like is a timer event. (a) False (b) True
  14. 14.👆 The user taps the button 2 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  15. 15.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi, Zoya! (b) Zoya (c) Hi, nameBox.text! (d) Hi!
  16. 16.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  17. 17.👆 A tap handler runs how many times if the user taps 4 times? (a) 8 (b) 1 (c) 4 (d) 0
  18. 18.👆 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
  19. 19.👆 Which of these is an event? (a) a list of names (b) the user taps a button (c) the icon colour (d) the font size
  20. 20.👆 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! (b) Hello, Aman! (c) Hello, nameBox.text! (d) Aman
  21. 21.True or false: one second passes is a timer event. (a) False (b) True
  22. 22.👆 What kind of event is this: a 5-minute alarm ends? (a) a text event (b) a timer event (c) a tap event (d) a load event
  23. 23.👆 The user taps the button 6 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  24. 24.👆 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;
    };
  25. 25.True or false: a countdown hits zero is a timer event. (a) False (b) True
  26. 26.👆 What kind of event is this: the user types a letter? (a) a timer event (b) a load event (c) a tap event (d) a text event
  27. 27.👆 “On tap → do this” links an event to ___. (a) a web address (b) a charger (c) an action (d) a font
  28. 28.👆 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;
    };
  29. 29.👆 What kind of event is this: one second passes? (a) a load event (b) a text event (c) a timer event (d) a tap event
  30. 30.👆 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
  31. 31.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 2;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  32. 32.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 7;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  33. 33.👆 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, nameBox.text! (b) Welcome, Zoya! (c) Welcome! (d) Zoya
  34. 34.👆 What kind of event is this: the user presses Save? (a) a load event (b) a tap event (c) a timer event (d) a text event
  35. 35.👆 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, nameBox.text! (c) Aman (d) Well done!
  36. 36.True or false: the user presses Save is a tap event. (a) True (b) False
  37. 37.👆 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! (b) Zoya (c) Hello, Zoya! (d) Hello, 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 < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  39. 39.True or false: the app starts up is a text event. (a) False (b) True
  40. 40.👆 The user taps the button 5 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };

Answer key

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

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