App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 241 · 40 questions

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.

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

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