App Dev Worksheet: Events

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

Answer key

a tap event
Hello, Aman!
OFF
4
ON
1
1
ON
Hi, Meera!
3
23
3
True
Well done, Riya!
a text event
14
Well done, Zoya!
False
ON
handler
18
OFF
something that happens
3
Well done, Arjun!
a timer event
3
a tap event
a timer event
Hello, Zoya!
Hi, Aman!
16
2
Well done, Aman!
Hello, Riya!
True
OFF
13
a timer event
4

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