【iOS】First Taste of Swift with Playgrounds

mark，记录之前写的基础swift代码。后续记得整理swift开发的demo APP。

import UIKit

var str = "Hello, playground"

let constant = 10
var number = 10
var result = number + constant

//constant = 20
// Cannot assign to value: 'constant' is a 'let' constant

number = 50

var message = "The best way to get started is to stop talking and code."

var greeting = "Hello "
var name = "Yofer"
message = greeting + name

message.uppercased()
message.lowercased()

message.count

var bookPrice = 39
var numOfCopies = 5
var totalPrice = bookPrice * numOfCopies
//var totalPriceMessage = "The price of the book is $" + totalPrice
// Binary operator '+' cannot be applied to operands of type 'String' and 'Int'

var totalPriceMessage = "The price of the book is $" + String(totalPrice)

totalPriceMessage = "The price of the book is $\(totalPrice)"



var timeYouWakeUp = 6

if timeYouWakeUp == 6 {
    print("Cook yourself a big breakfast")
} else {
    print("Go out for breakfast")
}


switch timeYouWakeUp {
case 6:
    print("Cook yourself a big breakfast")
default:
    print("Go out for breakfast")
}


var bonus = 5000

if bonus >= 10000 {
    print("I will travel to Paris and London!")
} else if bonus >= 5000 && bonus < 10000 {
    print("I will travel to Tokyo")
} else if bonus >= 1000 && bonus < 5000 {
    print("I will travel to Bangkok")
} else {
    print("Just stay home")
}


do {
    var bonus = 5000
    // Variable 'bonus' was never mutated; consider changing to 'let' constant
    
    switch bonus {
    case 10000...:
        print("I will travel to Paris and London!")
    case 5000...9999:
        print("I will travel to Tokyo")
    case 1000...4999:
        print("I will travel to Bangkok")
    default:
        print("Just stay home")
    }
}


//var bookCollection = ["Tool of Titans", "Rework", 1]
// error: heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional

var bookCollection = ["Tool of Titans", "Rework", "Your Move"]

bookCollection[0]

bookCollection.append("Authority")
bookCollection.count


print(bookCollection[0])
print(bookCollection[1])
print(bookCollection[2])
print(bookCollection[3])

for index in 0...3 {
    print(bookCollection[index])
}


for index in 0...bookCollection.count - 1 {
    print(bookCollection[index])
}

for book in bookCollection {
    print(book)
}


var bookCollectionDict = ["1328683788" : "Tool of Titans", "0307463745" : "Rework", "1612060919" : "Authority"]

bookCollectionDict["1328683788"]

bookCollectionDict["321"]

for (key, value) in bookCollectionDict {
    print("ISBN: \(key)")
    print("Title: \(value)")
}


var emojiDict = ["馃懟": "Ghost",
                 "馃挬": "Poop",
                 "馃槫": "Angry",
                 "馃槺": "Scream",
                 "馃懢": "Alien monster"]

var wordToLookup = "馃懟"
var meaning = emojiDict[wordToLookup]

print(meaning)
// Expression implicitly coerced from 'String?' to 'Any'

wordToLookup = "馃槫"
meaning = emojiDict[wordToLookup]

print(meaning)
// Expression implicitly coerced from 'String?' to 'Any'

meaning = emojiDict["馃槏"]
if let meaning = meaning {
    print(meaning)
}

let containerView = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
containerView.backgroundColor = UIColor.orange

let emojiLabel = UILabel(frame: CGRect(x: 95, y: 20, width: 150, height: 150))
emojiLabel.text = wordToLookup
emojiLabel.font = UIFont.systemFont(ofSize: 100.0)

containerView.addSubview(emojiLabel)

meaning = emojiDict[wordToLookup]
let meaningLabel = UILabel(frame: CGRect(x: 110, y: 100, width: 150, height: 150))
meaningLabel.text = meaning
meaningLabel.font = UIFont.systemFont(ofSize: 30.0)
meaningLabel.textColor = UIColor.white
containerView.addSubview(meaningLabel)


//var testVarValue
// error: type annotation missing in pattern
//let testLetValue
// error: type annotation missing in pattern

var jobTitle: String?
jobTitle = "iOS Developer"

//var jobMessage = "Your job title is " + jobTitle
// error: value of optional type 'String?' must be unwrapped to a value of type 'String'

// Forced Unwrapping
if jobTitle != nil {
    var jobMessage = "Your job title is " + jobTitle!
}


//jobTitle = nil
//var jobMessage = "Your job title is " + jobTitle!
// error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).


// Optional Binding
if let jotTitleWithValue = jobTitle {
    var message = "Your job title is " + jotTitleWithValue
}

if let jobTitle = jobTitle {
    var message = "Your job title is " + jobTitle
}

jobTitle = nil;
if let jobTitle = jobTitle {
    // never execute
    var message = "Your job title is " + jobTitle
}