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App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 50 · 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 5 times. What number does the label show now?
    let score = 6;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  2. 2.👆 What kind of event is this: the user taps Play? (a) a text event (b) a tap event (c) a load event (d) a timer event
  3. 3.True or false: the app starts up is a load event. (a) False (b) True
  4. 4.👆 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;
    };
  5. 5.👆 The user taps the button 5 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  6. 6.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a timer event (c) a text event (d) a load event
  7. 7.👆 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! (c) Hi, Meera! (d) Hi, nameBox.text!
  8. 8.👆 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;
    };
  9. 9.👆 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) Riya (b) Welcome, nameBox.text! (c) Welcome, Riya! (d) Welcome!
  10. 10.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a timer event (c) a text event (d) a load event
  11. 11.👆 An event in an app is ___. (a) an app store (b) a colour theme (c) something that happens (d) a kind of list
  12. 12.👆 What kind of event is this: one second passes? (a) a tap event (b) a timer event (c) a text event (d) a load event
  13. 13.👆 What kind of event is this: the user types a letter? (a) a text event (b) a timer event (c) a tap event (d) a load event
  14. 14.👆 The user types Arjun 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, nameBox.text! (b) Well done! (c) Arjun (d) Well done, Arjun!
  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.👆 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.True or false: the app starts up is a timer event. (a) True (b) False
  18. 18.👆 What kind of event is this: the search box changes? (a) a load event (b) a timer event (c) a tap event (d) a text event
  19. 19.👆 The user types Meera 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) Meera (c) Welcome! (d) Welcome, Meera!
  20. 20.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 4 (c) 1 (d) 8
  21. 21.👆 The user taps the button 3 times. What number does the label show now?
    let score = 7;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
  22. 22.👆 The user taps the button 4 times. What number does the label show now?
    let coins = 6;
    button.onTap = function () {
      coins = coins + 4;
      label.text = coins;
    };
  23. 23.👆 The user taps the button 3 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  24. 24.True or false: a countdown hits zero is a timer event. (a) False (b) True
  25. 25.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  26. 26.👆 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;
    };
  27. 27.👆 What kind of event is this: the user presses Save? (a) a timer event (b) a tap event (c) a text event (d) a load event
  28. 28.👆 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;
    };
  29. 29.👆 What kind of event is this: a finger hits Like? (a) a load event (b) a timer event (c) a text event (d) a tap event
  30. 30.👆 Code that runs when an event happens is called a ___. (a) header (b) handler (c) headline (d) hashtag
  31. 31.👆 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) Kabir (b) Hi, nameBox.text! (c) Hi, Kabir! (d) Hi!
  32. 32.True or false: the user presses Save is a tap event. (a) True (b) False
  33. 33.👆 The user taps the button 4 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.👆 Which of these is an event? (a) a list of names (b) the icon colour (c) the font size (d) the user taps a button
  35. 35.👆 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;
    };
  36. 36.True or false: a finger hits Like is a timer event. (a) False (b) True
  37. 37.👆 The user taps the button 2 times. What number does the label show now?
    let score = 1;
    button.onTap = function () {
      score = score + 5;
      label.text = score;
    };
  38. 38.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 3;
    button.onTap = function () {
      lives = lives + 1;
      label.text = lives;
    };
  39. 39.👆 The user taps the button 5 times. What number does the label show now?
    let points = 7;
    button.onTap = function () {
      points = points + 2;
      label.text = points;
    };
  40. 40.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Well done, " + nameBox.text + "!";
    };     (a) Kabir (b) Well done, Kabir! (c) Well done, nameBox.text! (d) Well done!

Answer key

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

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