App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 133 · 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.👆 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;
   };
2. 2.👆 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) Arjun (b) Hello, nameBox.text! (c) Hello, Arjun! (d) Hello!
3. 3.👆 The user taps the button 5 times. What number does the label show now?
   let score = 1;
   button.onTap = function () {
     score = score + 1;
     label.text = score;
   };
4. 4.👆 The user taps the button 4 times. What number does the label show now?
   let coins = 4;
   button.onTap = function () {
     coins = coins + 1;
     label.text = coins;
   };
5. 5.👆 The user types Riya in nameBox and taps the button 1 time. What does the label show?
   button.onTap = function () {
     label.text = "Hi, " + nameBox.text + "!";
   }; (a) Hi, nameBox.text! (b) Hi, Riya! (c) Hi! (d) Riya
6. 6.👆 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;
   };
7. 7.👆 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
8. 8.👆 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
9. 9.👆 “On tap → do this” links an event to ___. (a) a font (b) a web address (c) an action (d) a charger
10. 10.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 1 (c) 8 (d) 4
11. 11.👆 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
12. 12.👆 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;
    };
13. 13.👆 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
14. 14.True or false: a countdown hits zero is a text event. (a) False (b) True
15. 15.👆 What kind of event is this: the user presses Save? (a) a load event (b) a tap event (c) a text event (d) a timer event
16. 16.👆 What kind of event is this: a finger hits Like? (a) a timer event (b) a text event (c) a tap event (d) a load event
17. 17.True or false: a finger hits Like is a text event. (a) True (b) False
18. 18.True or false: the screen first opens is a timer event. (a) True (b) False
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) ON (b) OFF
20. 20.👆 The user types Kabir 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) Kabir (c) Hello, Kabir! (d) Hello!
21. 21.👆 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
22. 22.👆 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) Arjun (b) Welcome, nameBox.text! (c) Welcome, Arjun! (d) Welcome!
23. 23.👆 What kind of event is this: a countdown hits zero? (a) a tap event (b) a timer event (c) a load event (d) a text event
24. 24.👆 The user types Meera 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, Meera! (b) Meera (c) Well done, nameBox.text! (d) Well done!
25. 25.True or false: the user presses Save is a timer event. (a) True (b) False
26. 26.👆 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
27. 27.True or false: the user presses Save is a text event. (a) True (b) False
28. 28.👆 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, nameBox.text! (b) Hi, Meera! (c) Hi! (d) Meera
29. 29.👆 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) Well done! (b) Kabir (c) Well done, Kabir! (d) Well done, nameBox.text!
30. 30.👆 An event in an app is ___. (a) something that happens (b) a kind of list (c) an app store (d) a colour theme
31. 31.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 7;
    button.onTap = function () {
      lives = lives + 2;
      label.text = lives;
    };
32. 32.True or false: the user taps Play is a text event. (a) False (b) True
33. 33.True or false: a countdown hits zero is a tap event. (a) False (b) True
34. 34.👆 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;
    };
35. 35.👆 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) Aman (b) Hello, Aman! (c) Hello! (d) Hello, nameBox.text!
36. 36.👆 What kind of event is this: the screen first opens? (a) a tap event (b) a timer event (c) a load event (d) a text event
37. 37.👆 The user taps the button 5 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
38. 38.👆 The user taps the button 2 times. What number does the label show now?
    let score = 7;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };
39. 39.👆 The user types Riya 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! (b) Riya (c) Well done, Riya! (d) Well done, nameBox.text!
40. 40.👆 The user taps the button 6 times. What number does the label show now?
    let score = 5;
    button.onTap = function () {
      score = score + 2;
      label.text = score;
    };

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