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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 111 · 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 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! (c) Aman (d) Well done, nameBox.text!
  2. 2.👆 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;
    };
  3. 3.👆 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
  4. 4.👆 What kind of event is this: the user taps Play? (a) a load event (b) a text event (c) a timer event (d) a tap event
  5. 5.True or false: the user presses Save is a timer event. (a) False (b) True
  6. 6.👆 An event in an app is ___. (a) a colour theme (b) an app store (c) something that happens (d) a kind of list
  7. 7.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 4;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  8. 8.True or false: a 5-minute alarm ends is a text event. (a) True (b) False
  9. 9.👆 What kind of event is this: a finger hits Like? (a) a tap event (b) a load event (c) a text event (d) a timer event
  10. 10.👆 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
  11. 11.True or false: a countdown hits zero is a load event. (a) False (b) True
  12. 12.👆 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) Kabir (b) Welcome, Kabir! (c) Welcome, nameBox.text! (d) Welcome!
  13. 13.True or false: a finger hits Like is a text event. (a) True (b) False
  14. 14.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  15. 15.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  16. 16.👆 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
  17. 17.👆 The user taps the button 5 times. What number does the label show now?
    let points = 5;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  18. 18.True or false: the screen first opens is a load event. (a) True (b) False
  19. 19.👆 The user taps the button 6 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  20. 20.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 3;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  21. 21.True or false: the app starts up is a load event. (a) True (b) False
  22. 22.👆 The user taps the button 6 times. What number does the label show now?
    let points = 8;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  23. 23.True or false: the screen first opens is a text event. (a) True (b) False
  24. 24.👆 Code that runs when an event happens is called a ___. (a) handler (b) headline (c) hashtag (d) header
  25. 25.👆 What kind of event is this: the user presses Save? (a) a text event (b) a tap event (c) a load event (d) a timer event
  26. 26.👆 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) ON (b) OFF
  27. 27.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 2;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  28. 28.👆 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, nameBox.text! (b) Welcome! (c) Arjun (d) Welcome, Arjun!
  29. 29.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  30. 30.👆 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! (d) Hi, nameBox.text!
  31. 31.👆 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;
    };
  32. 32.👆 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
  33. 33.👆 What kind of event is this: a countdown hits zero? (a) a tap event (b) a load event (c) a timer event (d) a text event
  34. 34.👆 The user taps the button 4 times. What number does the label show now?
    let points = 2;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  35. 35.👆 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
  36. 36.👆 Which of these is an event? (a) the icon colour (b) a list of names (c) the font size (d) the user taps a button
  37. 37.True or false: the user taps Play is a timer event. (a) True (b) False
  38. 38.👆 What kind of event is this: a 5-minute alarm ends? (a) a text event (b) a load event (c) a tap event (d) a timer event
  39. 39.👆 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, nameBox.text! (b) Hello! (c) Zoya (d) Hello, Zoya!
  40. 40.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };

Answer key

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

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