App Dev Worksheet: Events

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

NameDateTime takenScore ___ / 40

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

Answer key

3
False
Hi, Aman!
16
12
an action
False
a timer event
ON
9
the user taps a button
5
a timer event
a tap event
Well done, Arjun!
1
Hi, Zoya!
handler
1
a tap event
False
Welcome, Arjun!
15
Well done, Aman!
something that happens
8
False
ON
a text event
7
OFF
4
2
True
a timer event
16
5
5
ON
2

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