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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 120 · 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 screen first opens is a load event. (a) True (b) False
  2. 2.👆 The user taps the button 6 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  3. 3.👆 Which of these is an event? (a) the icon colour (b) the font size (c) a list of names (d) the user taps a button
  4. 4.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a text event (c) a load event (d) a tap event
  5. 5.👆 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) ON (b) OFF
  6. 6.👆 “On tap → do this” links an event to ___. (a) a web address (b) a font (c) an action (d) a charger
  7. 7.👆 The user taps the button 5 times. What number does the label show now?
    let score = 9;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  8. 8.True or false: the search box changes is a tap event. (a) True (b) False
  9. 9.👆 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) Hello, nameBox.text! (c) Zoya (d) Hello, Zoya!
  10. 10.👆 The user taps the button 6 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  11. 11.👆 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;
    };
  12. 12.👆 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;
    };
  13. 13.👆 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
  14. 14.True or false: a 5-minute alarm ends is a tap event. (a) False (b) True
  15. 15.👆 An event in an app is ___. (a) something that happens (b) a colour theme (c) an app store (d) a kind of list
  16. 16.👆 Code that runs when an event happens is called a ___. (a) header (b) headline (c) handler (d) hashtag
  17. 17.👆 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;
    };
  18. 18.👆 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) OFF (b) ON
  19. 19.👆 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, Kabir! (b) Kabir (c) Hello! (d) Hello, nameBox.text!
  20. 20.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 2;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  21. 21.True or false: a finger hits Like is a text event. (a) False (b) True
  22. 22.👆 What kind of event is this: the search box changes? (a) a timer event (b) a tap event (c) a text event (d) a load event
  23. 23.👆 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
  24. 24.👆 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;
    };
  25. 25.👆 The user taps the button 5 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  26. 26.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 4;
    button.onTap = function () {
      stars = stars + 1;
      label.text = stars;
    };
  27. 27.True or false: one second passes is a timer event. (a) True (b) False
  28. 28.👆 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) Zoya (c) Welcome, Zoya! (d) Welcome!
  29. 29.👆 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
  30. 30.True or false: the user taps Play is a load event. (a) True (b) False
  31. 31.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a timer event (c) a load event (d) a text event
  32. 32.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  33. 33.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 0;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  34. 34.👆 The user taps the button 6 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  35. 35.👆 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) Hello, Riya! (c) Riya (d) Hello!
  36. 36.👆 The user taps the button 6 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  37. 37.👆 The user taps the button 3 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  38. 38.👆 What kind of event is this: the user presses Save? (a) a load event (b) a text event (c) a timer event (d) a tap event
  39. 39.👆 The user taps the button 5 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  40. 40.👆 What kind of event is this: the user types a letter? (a) a load event (b) a timer event (c) a text event (d) a tap event

Answer key

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

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