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[swift/en] Fix typos
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@ -91,7 +91,7 @@ let multiLineString = """
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This is a multi-line string.
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It's called that because it takes up multiple lines (wow!)
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Any indentation beyond the closing quotation marks is kept, the rest is discarded.
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You can include " or "" in multi-line strings because the delimeter is three "s.
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You can include " or "" in multi-line strings because the delimiter is three "s.
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"""
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// Arrays
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@ -159,12 +159,12 @@ let `class` = "keyword"
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or contains nil (no value) to indicate that a value is missing.
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Nil is roughly equivalent to `null` in other languages.
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A question mark (?) after the type marks the value as optional of that type.
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If a type is not optional, it is guaranteed to have a value.
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Because Swift requires every property to have a type, even nil must be
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explicitly stored as an Optional value.
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Optional<T> is an enum, with the cases .none (nil) and .some(T) (the value)
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*/
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@ -178,7 +178,7 @@ let someOptionalString4 = String?.none //nil
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To access the value of an optional that has a value, use the postfix
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operator !, which force-unwraps it. Force-unwrapping is like saying, "I
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know that this optional definitely has a value, please give it to me."
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Trying to use ! to access a non-existent optional value triggers a
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runtime error. Always make sure that an optional contains a non-nil
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value before using ! to force-unwrap its value.
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@ -194,7 +194,7 @@ if someOptionalString != nil {
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// Swift supports "optional chaining," which means that you can call functions
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// or get properties of optional values and they are optionals of the appropriate type.
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// You can even do this multiple times, hence the name "chaining."
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let empty = someOptionalString?.isEmpty // Bool?
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// if-let structure -
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@ -370,7 +370,7 @@ func say(_ message: String) {
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}
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say("Hello")
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// Default parameters can be ommitted when calling the function.
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// Default parameters can be omitted when calling the function.
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func printParameters(requiredParameter r: Int, optionalParameter o: Int = 10) {
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print("The required parameter was \(r) and the optional parameter was \(o)")
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}
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@ -443,7 +443,7 @@ func testGuard() {
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return // guard statements MUST exit the scope that they are in.
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// They generally use `return` or `throw`.
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}
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print("number is \(aNumber)")
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}
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testGuard()
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@ -564,7 +564,7 @@ enum Furniture {
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case desk(height: Int)
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// Associate with String and Int
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case chair(String, Int)
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func description() -> String {
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//either placement of let is acceptable
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switch self {
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@ -591,15 +591,15 @@ print(chair.description()) // "Chair of Foo with 40 cm"
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- Define initializers to set up their initial state
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- Be extended to expand their functionality beyond a default implementation
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- Conform to protocols to provide standard functionality of a certain kind
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Classes have additional capabilities that structures don't have:
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- Inheritance enables one class to inherit the characteristics of another.
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- Type casting enables you to check and interpret the type of a class instance at runtime.
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- Deinitializers enable an instance of a class to free up any resources it has assigned.
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- Reference counting allows more than one reference to a class instance.
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Unless you need to use a class for one of these reasons, use a struct.
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Structures are value types, while classes are reference types.
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*/
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@ -607,7 +607,7 @@ print(chair.description()) // "Chair of Foo with 40 cm"
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struct NamesTable {
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let names: [String]
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// Custom subscript
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subscript(index: Int) -> String {
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return names[index]
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@ -629,7 +629,7 @@ class Shape {
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class Rect: Shape {
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var sideLength: Int = 1
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// Custom getter and setter property
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var perimeter: Int {
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get {
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@ -640,16 +640,16 @@ class Rect: Shape {
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sideLength = newValue / 4
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}
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}
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// Computed properties must be declared as `var`, you know, cause' they can change
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var smallestSideLength: Int {
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return self.sideLength - 1
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}
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// Lazily load a property
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// subShape remains nil (uninitialized) until getter called
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lazy var subShape = Rect(sideLength: 4)
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// If you don't need a custom getter and setter,
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// but still want to run code before and after getting or setting
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// a property, you can use `willSet` and `didSet`
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@ -659,19 +659,19 @@ class Rect: Shape {
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print(someIdentifier)
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}
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}
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init(sideLength: Int) {
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self.sideLength = sideLength
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// always super.init last when init custom properties
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super.init()
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}
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func shrink() {
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if sideLength > 0 {
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sideLength -= 1
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}
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}
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override func getArea() -> Int {
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return sideLength * sideLength
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}
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@ -703,13 +703,13 @@ class Circle: Shape {
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override func getArea() -> Int {
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return 3 * radius * radius
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}
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// Place a question mark postfix after `init` is an optional init
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// which can return nil
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init?(radius: Int) {
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self.radius = radius
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super.init()
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if radius <= 0 {
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return nil
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}
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@ -813,7 +813,7 @@ for _ in 0..<10 {
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- Internal: Accessible and subclassible in the module it is declared in.
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- Fileprivate: Accessible and subclassible in the file it is declared in.
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- Private: Accessible and subclassible in the enclosing declaration (think inner classes/structs/enums)
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See more here: https://docs.swift.org/swift-book/LanguageGuide/AccessControl.html
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*/
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@ -878,11 +878,11 @@ extension Int {
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var doubled: Int {
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return self * 2
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}
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func multipliedBy(num: Int) -> Int {
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return num * self
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}
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mutating func multiplyBy(num: Int) {
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self *= num
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}
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@ -965,18 +965,18 @@ func fakeFetch(value: Int) throws -> String {
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guard 7 == value else {
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throw MyError.reallyBadValue(msg: "Some really bad value")
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}
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return "test"
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}
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func testTryStuff() {
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// assumes there will be no error thrown, otherwise a runtime exception is raised
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let _ = try! fakeFetch(value: 7)
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// if an error is thrown, then it proceeds, but if the value is nil
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// it also wraps every return value in an optional, even if its already optional
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let _ = try? fakeFetch(value: 7)
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do {
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// normal try operation that provides error handling via `catch` block
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try fakeFetch(value: 1)
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