ソフトウェアエンジニアの技術ブログ：Software engineer tech blog – Page 610 – 随机应变 ABCD: Always Be Coding and … : хороший

what’s string about

let theTrueth = "Money can't buy me love."
theTruth.characters.count

var forwardString = "spoons"
var charactersReversed = forwardString.characters.reversed()

for character in charactersReversed {
	print ("\(character)")
}

let similarTruth = "can't buy me"

var birthdayCheer = "Happy Birthday!"
print(birthdayCheer)

var name = "Kate"
var customizedBirthdayCheer = "Happy Birthday, \(name)!"
print(customizedBirthdayCheer)

var doggyDiet = "Mia eats 10 lbs of dog food per month."

var dogName = "Zebedee"
var lbsPerMonth: Double = 25

doggyDiet = "\(dogName) eats \(lbsPerMonth)lbs of dog food per month"

print(doggyDiet)

var kilosInALb = 0.45
var metricDoggyDiet = "\(dogName) eats \(kilosInALb * lbsPerMonth)kilos of dog food per month"

print(metricDoggyDiet)

let monkeyString = "I saw a monkey."
let thiefString = "He stole my iPhone."

var monkeyStringWithEmoji = "I saw a *."
var thiefStringWithEmoji = "He stole my *."

var forwardString = "time"
var charactersReversed = forwardString.characters.reversed()

for character in charactersReversed {
	print("\(character)")
}

let numOfPennies = 567
let dollarInt = numofPennies/100
let dollarsAndCentsString = "$\(dollarInt).\(numOfPennies % 100)"

let monkeyString = "I saw a monkey."
let thiefString = "He stole my iPhone."
var sillyMonkeyString = monkeyString + "" + thiefString

replacingOccurences(of: with:)

sillyMonkeyString.contains("key")

Different types of variables

var petsAge = 12
var myMiddleInitial: Character = "A"
var numberOfWheels: Int = 4
var centimetersOfRainfall: Float = 5.5
var pi: Double = 3.14159265359
var letterOfTheDay: Character = "z"
var myFavoriteAnimal: String = "nudibranch"
var rainingOutside: Bool = true

let encouragement = "you can do it!"
var customizedEncouragement = "you can do it, stephanie!"
customizedEncouragement = "you can do it, Ryder!"

let birthYear = 2008
var currentYear = 2017
var age = currentYear - birthYear
currentYear = 2017
age = currentYear - birthYear

Names cannot contain whitespace characters, mathematical symbols, arrows and [a few other obscure characters].
Names must begin with an uppercase or lowercase letter A through Z, an underscore, or [a few other less common options].

let theTrue = "Money can't buy me love."

var characterPoorString = ""
let stringWithPotential = String()

Sandbox

// test code here!
print((200 * 7)/2)

print("hello from iOS team")

var question = "Ready to write your first lines of Swift code?"
print(question)

var response = "Yeah! I'm ready!"
print(response)

var numberOfServingsForRecipe = 4
var desiredNumberOfServings = 8

var servingsFactor = desiredNumberOfServings/numberOfServingsForRecipe

var poundsOfTomatoesForRecipe = 2
var amountToUseToday = poundsOfTomatoesForRecipe * servingsFactor

print(amountToUseToday)

Drawing to code

step1: select the views
step2: position the views
step3: style the views

what view group should you use
-LinearLayout
-RelativeLayout : relative positioning, overlap

The drawable folder
android:src=”@drawable/androidparty”

Position the view
Style the view

Trouble shooting

android studio strouble shooting
https://docs.google.com/document/d/1w1Xn_hnSAODAAtdRDp7haYPBtEwX_l7Htpf8Wpgbu6w/pub?embedded=true

Linear layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:paddingBottom="@dimen/activity_vertical_margin"
	android:paddingLeft="@dimen/activity_horizontal_margin"
	android:paddingRight="@dimen/activity_horizontal_margin"
	android:paddingTop="@dimen/activity_vertical_margin"
	tools:context="com.xxx.myapplication.MainActivity">

	<TextView
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="Hello world!" />
</RelativeLayout>

Relative Layout

top edge, left edge, right edge, buttom edge
relative to parent

android:layout_alignParentTop=”true”
android:layout_alignParentBottom=”false”
android:layout_alignParentLeft=”true”
android:layout_alignParentRight=”true”

<RelativeLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:padding="16dp">

	<TextView
		android:text="I'm in this corner"
		android:layout_height="wrap_content"
		android:layout_width="wrap_content"
		android:layout_alignParentBottom="true"
		android:layout_alignParentLeft="true" />

    <TextView
        android:text="No, up here"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true" />
 
    <TextView
        android:text="Wait, I’m here"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true" />
 
    <TextView
        android:text="Actually, I’m here"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true" />

</RelativeLayout>

Simple image view

<ImageView
	android:src="@drawable/cake"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:scaleType="center"/>

<ImageView
	android:src="@drawable/cake"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:scaleType="centerCrop"/>

textView android, use google search
https://developer.android.com/reference/android/widget/TextView.html

capitalize

<TextView
	android:text="Oh the possibilites of TextView"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:textSize="36sp"
	android:textAllCaps="false"/>

LinearLayout

<LinearLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content">

<TextView
	android:text="I'm a lonely TextView"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content" />

<TextView
	android:text="I'm a lonely TextView"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content" />

</LinearLayout>

android orientation
https://developer.android.com/reference/android/widget/LinearLayout.html

200dp, wrap_content, match_parent

wrap_content

<TextView
	android:text="wait, today's your birthday?"
	android:background="@android:color/darker_gray"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content" />

font size

<TextView
	android:text="wait, today's your birthday?"
	android:background="@android:color/darker_gray"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:textSize="56sp" />

appearance

<TextView
	android:text="wait, today's your birthday?"
	android:background="@android:color/darker_gray"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:textAppearance="?android:textAppearanceSmall" />

google design spec style color
https://material.io/guidelines/style/color.html

text color and background color

<TextView
	android:text="wait, today's your birthday?"
	android:background="#ECEFF1"
	android:textColor="#616161"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:textAppearance="?android:textAppearanceSmall" />

Using a TextView

<TextView
	android:text="Happy Birthday!"
	android:background="@android:color/darker_gray"
	android:layout_width="150dp"
	android:layout_height="75dp" />

-weird angle brackets
-don’t know what “android:text” means
-says Happy Birthday which appears on phone

XML Syntax

<LinearLayout
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:orientation="vertical">

	<TextView
		android:text="Happy Birthday"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content" />

	<TextView
		android:text="You're the best!"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content" />

</LinearLayout>

Attribute Name, Attribute value in “Quotations”
TextView has default values if you’re ok with default values, don’t set them here.

negative correlation

How much two variable related each other.
always use correlation in statistic.
x= 3, 4, 5
y= 8, 5, 3

r = Σi[(xi-x)(yi-y)] / √Σi[(xi-x)(yi-y)]
x=1/N　Σ Xi
y=1/N　Σ Yi

x-x -1, 0, 1
y-y 3, 0, -3

= -6 / √ 2 * 18
= -1

x= 3, 4, 5
y= 8, 5, 8
r= 0

x= 3, 4, 5 xμ = 4
y= 8, 3, 7 yμ = 6

x-x -1, 0, 1
y-y 2, -3, 1

= -1 / √ 2 * 14
=　-0.189