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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 76 · 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.👆 Which of these is an event? (a) the font size (b) the icon colour (c) a list of names (d) the user taps a button
  2. 2.👆 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, Aman! (b) Hi, nameBox.text! (c) Hi! (d) Aman
  3. 3.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello, Aman! (b) Aman (c) Hello, nameBox.text! (d) Hello!
  4. 4.👆 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
  5. 5.👆 A tap handler runs how many times if the user taps 4 times? (a) 4 (b) 8 (c) 0 (d) 1
  6. 6.👆 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;
    };
  7. 7.👆 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
  8. 8.👆 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
  9. 9.👆 An event in an app is ___. (a) something that happens (b) an app store (c) a kind of list (d) a colour theme
  10. 10.👆 The user taps the button 5 times. What number does the label show now?
    let score = 4;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  11. 11.👆 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
  12. 12.👆 What kind of event is this: the user taps Play? (a) a tap event (b) a load event (c) a timer event (d) a text event
  13. 13.👆 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;
    };
  14. 14.👆 The user taps the button 5 times. What number does the label show now?
    let points = 8;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  15. 15.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) an action (d) a charger
  16. 16.👆 What kind of event is this: the search box changes? (a) a load event (b) a tap event (c) a timer event (d) a text event
  17. 17.👆 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) Hi! (b) Meera (c) Hi, Meera! (d) Hi, nameBox.text!
  18. 18.👆 The user taps the button 2 times. What number does the label show now?
    let coins = 1;
    button.onTap = function () {
      coins = coins + 5;
      label.text = coins;
    };
  19. 19.True or false: the user types a letter is a tap event. (a) False (b) True
  20. 20.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 4;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  21. 21.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a load event (c) a text event (d) a timer event
  22. 22.👆 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;
    };
  23. 23.👆 What kind of event is this: a 5-minute alarm ends? (a) a load event (b) a tap event (c) a text event (d) a timer event
  24. 24.👆 The user taps the button 4 times. What number does the label show now?
    let points = 4;
    button.onTap = function () {
      points = points + 3;
      label.text = points;
    };
  25. 25.👆 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) Hi, nameBox.text! (c) Zoya (d) Hi!
  26. 26.👆 The user taps the button 6 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  27. 27.👆 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) Arjun (c) Welcome, Arjun! (d) Welcome!
  28. 28.👆 The user taps the button 3 times. What number does the label show now?
    let coins = 4;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  29. 29.👆 The user types Arjun in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hi, " + nameBox.text + "!";
    };     (a) Arjun (b) Hi! (c) Hi, Arjun! (d) Hi, nameBox.text!
  30. 30.👆 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;
    };
  31. 31.👆 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
  32. 32.👆 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
  33. 33.👆 What kind of event is this: the user types a letter? (a) a load event (b) a text event (c) a tap event (d) a timer event
  34. 34.👆 The user taps the button 6 times. What number does the label show now?
    let score = 10;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  35. 35.👆 What kind of event is this: the user presses Save? (a) a text event (b) a tap event (c) a timer event (d) a load event
  36. 36.👆 Code that runs when an event happens is called a ___. (a) headline (b) header (c) handler (d) hashtag
  37. 37.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 5;
    button.onTap = function () {
      coins = coins + 1;
      label.text = coins;
    };
  38. 38.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  39. 39.True or false: a finger hits Like is a tap event. (a) True (b) False
  40. 40.True or false: the user taps Play is a tap event. (a) False (b) True

Answer key

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

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