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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 289 · 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 search box changes is a timer event. (a) False (b) True
  2. 2.👆 What kind of event is this: a countdown hits zero? (a) a tap event (b) a text event (c) a load event (d) a timer event
  3. 3.True or false: the app starts up is a timer event. (a) True (b) False
  4. 4.True or false: one second passes is a timer event. (a) True (b) False
  5. 5.👆 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, Zoya! (c) Zoya (d) Hello, nameBox.text!
  6. 6.True or false: a finger hits Like is a tap event. (a) False (b) True
  7. 7.👆 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;
    };
  8. 8.👆 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;
    };
  9. 9.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  10. 10.👆 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
  11. 11.👆 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
  12. 12.👆 The user taps the button 4 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  13. 13.True or false: the user taps Play is a tap event. (a) True (b) False
  14. 14.True or false: the search box changes is a tap event. (a) True (b) False
  15. 15.👆 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
  16. 16.👆 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
  17. 17.👆 The user taps the button 3 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  18. 18.👆 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) Aman (c) Hi, Aman! (d) Hi, nameBox.text!
  19. 19.👆 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
  20. 20.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 5;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
  21. 21.👆 What kind of event is this: one second passes? (a) a timer event (b) a tap event (c) a text event (d) a load event
  22. 22.👆 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;
    };
  23. 23.👆 An event in an app is ___. (a) a colour theme (b) a kind of list (c) something that happens (d) an app store
  24. 24.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 5;
    button.onTap = function () {
      coins = coins + 3;
      label.text = coins;
    };
  25. 25.👆 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;
    };
  26. 26.👆 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;
    };
  27. 27.👆 The user taps the button 2 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  28. 28.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  29. 29.👆 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
  30. 30.👆 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;
    };
  31. 31.True or false: a countdown hits zero is a timer event. (a) False (b) True
  32. 32.👆 The user taps the button 5 times. What number does the label show now?
    let points = 10;
    button.onTap = function () {
      points = points + 4;
      label.text = points;
    };
  33. 33.👆 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;
    };
  34. 34.👆 “On tap → do this” links an event to ___. (a) a web address (b) a font (c) an action (d) a charger
  35. 35.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  36. 36.True or false: a finger hits Like is a timer event. (a) False (b) True
  37. 37.👆 The user taps the button 4 times. What number does the label show now?
    let points = 6;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  38. 38.👆 Code that runs when an event happens is called a ___. (a) handler (b) headline (c) header (d) hashtag
  39. 39.👆 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;
    };
  40. 40.👆 The user taps the button 4 times. What number does the label show now?
    let stars = 9;
    button.onTap = function () {
      stars = stars + 2;
      label.text = stars;
    };

Answer key

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

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