Swift 基礎入門：掌握這門現代程式語言的核心概念與實用技巧

摘要

本文將帶您了解 Swift 語言的基礎知識及其在當今軟體開發中的重要性，幫助讀者快速掌握這門現代程式語言。 歸納要點:

• Swift 語言迅速崛起,成為現代軟體開發的首選語言,其簡潔和安全性大幅提升了開發效率。
• 深入探討 Swift 中的進階資料結構與演算法,有助於優化應用效能及資料處理能力,滿足高效能需求。
• Swift 與 SwiftUI 的整合推動了跨平台應用程式開發的新趨勢,使得開發者能更輕鬆地打造多元化產品。

我們在研究許多文章後,彙整重點如下

React Native 中的第三方元件擴充應用功能

React Native 架構與原生模組最佳化：效能提升訣竅

React Native 與 Swift：跨平台開發的創新結合

let constantValue = 10 var mutableValue = 0

let constantValue = 10 var mutableValue = 0  constantValue = 20  Output:  Error: error: cannot assign to value: 'constantValue' is a 'let' constant note: change 'let' to 'var' to make it mutable.

let constantValue: Int; var mutableValue = 0  constantValue = 20

 let constantValue; var mutableValue = 0  constantValue = 20  Output: error: type annotation missing in pattern

let constantValue: Int; print(constantValue) var mutableValue = 0  constantValue = 20  Output: error: constant 'constantValue' used before being initialized

let constantValue: Int; var mutableValue = 0  constantValue = true;  Output: error: cannot assign the value of type 'Bool' to type 'Int'.

var x = 0.0, y = 0.0, z = 0.0 var red, green, blue: String

let name = "Varun"

var globalVariable = "Global Scope"  func testFunction() {     var localVariable = "Local Scope"          print(globalVariable) // This will print "Global Scope"     print(localVariable)  // This will print "Local Scope"          var globalVariable = "Shadowed Local Scope"          print(globalVariable) // This will print "Shadowed Local Scope" }  testFunction()  print(globalVariable) // This will print "Global Scope"

let name = "Varun"; print(name); //Prints Varun print("My name is \(name)") //Prints My name is Varun

//Single line comment  /* Multi line comment Multi Line comment */ 

SWIFT 資料型態：多樣選擇，提升程式碼可驗證性

UInt8 UInt16 UInt32 UInt64

Int8 Int16 Int32 Int64

let cannotBeNegative: UInt8 = -1 // UInt8 can't store negative numbers, and so this will report an error let tooBig: Int8 = Int8.max + 1 // Int8 can't store a number larger than its maximum value, // and so this will also report an error

let i: Int = -2; let j: UInt = 0;

iOS中資料型別的最佳化

let value: Float = 0.7767668788  print(value) //Prints 0.7767669

let value: Double = 0.7767668788  print(value) //Prints 0.7767668788

let pi = 3.14159 // pi is inferred to be of type Double

let decimalInteger = 17 let binaryInteger = 0b10001 let octalInteger = 0o21 let hexadecimalInteger = 0x11   print(decimalInteger, binaryInteger, octalInteger, hexadecimalInteger) //Prints 17 17 17 17

Swift 運運算元、模式匹配與錯誤處理新特性初探

let a = 20; let b = 23; let result = a < b ? "a less than b" : "b less than a";

let lowerBound = 1; let higherBound = 5; for index in lowerBound...higherBound {     print("\(index)") }  Output:  1 2 3 4 5

for index in 1...1 {     print("\(index)") }

let lowerBound = 1; let higherBound = 5; for index in lowerBound..

let array = ["a", "b", "c", "d", "e"] let slice = array[1...3] print(slice) //Prints ["b", "c", "d"] print(array) //Prints ["a", "b", "c", "d", "e"]

let array = ["a", "b", "c", "d", "e"] let slice1 = array[...3] print(slice1) // Prints ["a", "b", "c", "d"]  let slice2 = array[..<3] //this excludes the 3rd index and includes elements only upto index 2. print(slice2) // Prints ["a", "b", "c"]

let array = ["a", "b", "c", "d", "e"] let slice = array[3...] print(slice) // Prints ["d", "e"]

let array = ["a", "b", "c", "d", "e"] let slice = array[...] print(slice) // Prints ["a", "b", "c", "d", "e"]

for index in 1... {     print("\(index)") }

let Student = (33, "Varun");

print("The Roll number is \(Student.0)") // This accesses roll number 33 print("The Roll number is \(Student.1)") // This accesses name "Varun"

let (RollNumber, Name) = Student print("The Roll number code is \(RollNumber)")

let firstTuple = (1, "zebra"); let secondTuple = (1, "apple"); let result = firstTuple < secondTuple print("\(result)") //Prints false

let firstTuple = (1, "zebra"); let secondTuple = ("one", "apple"); let result = firstTuple < secondTuple print("\(result)")  //Output: error: cannot convert value of type '(String, String)' to specified type '(Int, String)'

let firstTuple = (1, "zebra"); let secondTuple = (1, "apple", "mango"); let result = firstTuple < secondTuple print("\(result)")  output: binary operator '<' cannot be applied to operands of type '(Int, String)' and '(Int, String, String)'

let firstTuple = (1, true); let secondTuple = (1, false); let result = firstTuple < secondTuple print("\(result)")  output: error: binary operator '<' cannot be applied to two '(Int, Bool)' operands

let firstTuple = (1, true); let secondTuple = (1, false); let result = firstTuple == secondTuple print("\(result)")  Output: false

let optionalValue1: Int? = 20; let optionalValue2: Int? = nil;

let optionalValue1: Int? = 20;  print(optionalValue1) //Prints Optional(20)

let optionalValue1: Int? = 20;  print(optionalValue1!) //Prints 20

let optionalValue1: Int? = nil;  print(optionalValue1!)   Output: Fatal error: Unexpectedly found nil while unwrapping an Optional value

let optionalValue1: Int? = 20;  if let optionalValue1 {     print("The optionalValue1 is: \(optionalValue1)") } else {     print("The optionalValue1 was nil") }  Output: The optionalValue1 is: 20

let optionalValue1: Int? = nil;  if let optionalValue1 {     print("The optionalValue1 is: \(optionalValue1)") } else {     print("The optionalValue1 was nil") }  Output: The optionalValue1 was nil

let optionalString: String? = nil let result = optionalString ?? "Test" print(result)  // Prints "Test"

let optionalString: String! = nil; optionalString = "Test"; print(optionalString)  // Prints "Test"