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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 324 · 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 types Riya 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! (b) Riya (c) Well done, Riya! (d) Well done, nameBox.text!
  2. 2.👆 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! (c) Welcome, Zoya! (d) Zoya
  3. 3.👆 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;
    };
  4. 4.👆 The user taps the button 3 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  5. 5.👆 The user taps the button 8 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  6. 6.True or false: the user types a letter is a load event. (a) True (b) False
  7. 7.True or false: the user taps Play is a load event. (a) True (b) False
  8. 8.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  9. 9.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) headline (c) header (d) handler
  10. 10.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) an action (d) a charger
  11. 11.👆 An event in an app is ___. (a) something that happens (b) a colour theme (c) an app store (d) a kind of list
  12. 12.True or false: one second passes is a load event. (a) False (b) True
  13. 13.👆 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;
    };
  14. 14.👆 What kind of event is this: the search box changes? (a) a load event (b) a tap event (c) a timer event (d) a text event
  15. 15.👆 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
  16. 16.👆 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;
    };
  17. 17.True or false: the search box changes is a load event. (a) False (b) True
  18. 18.👆 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
  19. 19.👆 Which of these is an event? (a) the font size (b) a list of names (c) the user taps a button (d) the icon colour
  20. 20.👆 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
  21. 21.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  22. 22.👆 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) Hello! (b) Hello, Kabir! (c) Kabir (d) Hello, nameBox.text!
  23. 23.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 4 (c) 8 (d) 1
  24. 24.👆 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! (b) Welcome, nameBox.text! (c) Welcome, Arjun! (d) Arjun
  25. 25.True or false: the screen first opens is a load event. (a) False (b) True
  26. 26.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, nameBox.text! (b) Riya (c) Hello! (d) Hello, Riya!
  27. 27.👆 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;
    };
  28. 28.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 9;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  29. 29.👆 What kind of event is this: the user presses Save? (a) a text event (b) a timer event (c) a load event (d) a tap event
  30. 30.👆 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;
    };
  31. 31.True or false: the app starts up is a load event. (a) False (b) True
  32. 32.👆 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;
    };
  33. 33.True or false: the app starts up is a timer event. (a) True (b) False
  34. 34.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi! (b) Hi, Aman! (c) Hi, nameBox.text! (d) Aman
  35. 35.👆 What kind of event is this: a countdown hits zero? (a) a tap event (b) a timer event (c) a load event (d) a text event
  36. 36.👆 What kind of event is this: a 5-minute alarm ends? (a) a text event (b) a tap event (c) a load event (d) a timer event
  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, Arjun! (c) Well done! (d) Well done, nameBox.text!
  38. 38.True or false: the user taps Play is a tap event. (a) False (b) True
  39. 39.👆 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;
    };
  40. 40.👆 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

Answer key

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

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