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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 157 · 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 3 times. What number does the label show now?
    let lives = 0;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  2. 2.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  3. 3.👆 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;
    };
  4. 4.👆 What kind of event is this: the app starts up? (a) a tap event (b) a load event (c) a timer event (d) a text event
  5. 5.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  6. 6.👆 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
  7. 7.👆 Code that runs when an event happens is called a ___. (a) headline (b) header (c) handler (d) hashtag
  8. 8.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 2;
      label.text = coins;
    };
  9. 9.👆 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) OFF (b) ON
  10. 10.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a load event (c) a timer event (d) a text event
  11. 11.👆 What kind of event is this: the user presses Save? (a) a text event (b) a load event (c) a timer event (d) a tap event
  12. 12.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome! (b) Riya (c) Welcome, nameBox.text! (d) Welcome, Riya!
  13. 13.True or false: the user taps Play is a tap event. (a) True (b) False
  14. 14.👆 The user taps the button 6 times. What number does the label show now?
    let score = 3;
    button.onTap = function () {
      score = score + 4;
      label.text = score;
    };
  15. 15.👆 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;
    };
  16. 16.👆 A tap handler runs how many times if the user taps 4 times? (a) 1 (b) 0 (c) 8 (d) 4
  17. 17.👆 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
  18. 18.True or false: a 5-minute alarm ends is a text event. (a) True (b) False
  19. 19.True or false: a finger hits Like is a timer event. (a) True (b) False
  20. 20.True or false: one second passes is a load event. (a) False (b) True
  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) OFF (b) ON
  22. 22.True or false: the screen first opens is a timer event. (a) False (b) True
  23. 23.👆 The user taps the button 2 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  24. 24.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 5;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  25. 25.👆 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;
    };
  26. 26.👆 What kind of event is this: the screen first opens? (a) a timer event (b) a load event (c) a text event (d) a tap event
  27. 27.👆 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
  28. 28.👆 What kind of event is this: the search box changes? (a) a text event (b) a tap event (c) a timer event (d) a load event
  29. 29.👆 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
  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.👆 Which of these is an event? (a) the icon colour (b) the font size (c) the user taps a button (d) a list of names
  32. 32.👆 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
  33. 33.👆 The user taps the button 6 times. What number does the label show now?
    let coins = 1;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  34. 34.👆 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;
    };
  35. 35.👆 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;
    };
  36. 36.👆 The user types Meera in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Meera (b) Hi, nameBox.text! (c) Hi, Meera! (d) Hi!
  37. 37.👆 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;
    };
  38. 38.True or false: the search box changes is a text event. (a) True (b) False
  39. 39.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 6;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  40. 40.👆 What kind of event is this: the user types a letter? (a) a tap event (b) a text event (c) a timer event (d) a load event

Answer key

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

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