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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 311 · 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.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 1 (c) 8 (d) 4
  2. 2.True or false: the user presses Save is a tap event. (a) False (b) True
  3. 3.👆 The user taps the button 2 times. What number does the label show now?
    let score = 2;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  4. 4.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  5. 5.👆 What kind of event is this: the user presses Save? (a) a timer event (b) a text event (c) a load event (d) a tap event
  6. 6.👆 What kind of event is this: a finger hits Like? (a) a timer event (b) a load event (c) a text event (d) a tap event
  7. 7.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  8. 8.👆 The user types Kabir 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, Kabir! (c) Welcome! (d) Kabir
  9. 9.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 5;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  10. 10.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, Meera! (b) Hello, nameBox.text! (c) Meera (d) Hello!
  11. 11.👆 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;
    };
  12. 12.👆 What kind of event is this: a 5-minute alarm ends? (a) a timer event (b) a text event (c) a tap event (d) a load event
  13. 13.👆 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
  14. 14.True or false: the user presses Save is a timer event. (a) True (b) False
  15. 15.👆 Which of these is an event? (a) the icon colour (b) the user taps a button (c) a list of names (d) the font size
  16. 16.True or false: the user presses Save is a load event. (a) True (b) False
  17. 17.👆 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;
    };
  18. 18.True or false: the user types a letter is a text event. (a) False (b) True
  19. 19.👆 The user taps the button 5 times. What number does the label show now?
    let stars = 8;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  20. 20.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  21. 21.👆 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
  22. 22.👆 “On tap → do this” links an event to ___. (a) an action (b) a web address (c) a font (d) a charger
  23. 23.👆 The user taps the button 2 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  24. 24.👆 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;
    };
  25. 25.True or false: a countdown hits zero is a timer event. (a) True (b) False
  26. 26.👆 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
  27. 27.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  28. 28.👆 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;
    };
  29. 29.True or false: the user presses Save is a text event. (a) False (b) True
  30. 30.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  31. 31.👆 What kind of event is this: the user taps Play? (a) a timer event (b) a text event (c) a tap event (d) a load event
  32. 32.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 3;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  33. 33.👆 An event in an app is ___. (a) a kind of list (b) a colour theme (c) an app store (d) something that happens
  34. 34.True or false: one second passes is a tap event. (a) False (b) True
  35. 35.👆 The user taps the button 6 times. What number does the label show now?
    let score = 8;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  36. 36.👆 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
  37. 37.👆 The user taps the button 6 times. What number does the label show now?
    let score = 5;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  38. 38.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 2;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  39. 39.👆 The user taps the button 3 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  40. 40.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Hi, nameBox.text! (b) Hi! (c) Kabir (d) Hi, Kabir!

Answer key

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

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