diff options
| author | Divay Prakash <divayprakash@users.noreply.github.com> | 2020-01-24 20:02:22 +0530 | 
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-01-24 20:02:22 +0530 | 
| commit | 9f41d38cec5fb891c5450a39a440b948eaf913e5 (patch) | |
| tree | 82636e5e18ad7df9636d7939e2aa1f6abecf58c9 /swift.html.markdown | |
| parent | 7e27297ea555764a5e690f251205d9323b349bb2 (diff) | |
| parent | 8e18975548d40ab0de6924ffac38127d7f01fecd (diff) | |
Merge branch 'master' into dart-formatting
Diffstat (limited to 'swift.html.markdown')
| -rw-r--r-- | swift.html.markdown | 56 | 
1 files changed, 28 insertions, 28 deletions
| diff --git a/swift.html.markdown b/swift.html.markdown index c2fb3471..1f9fe897 100644 --- a/swift.html.markdown +++ b/swift.html.markdown @@ -91,7 +91,7 @@ let multiLineString = """      This is a multi-line string.      It's called that because it takes up multiple lines (wow!)          Any indentation beyond the closing quotation marks is kept, the rest is discarded. -    You can include " or "" in multi-line strings because the delimeter is three "s. +    You can include " or "" in multi-line strings because the delimiter is three "s.      """  // Arrays @@ -159,12 +159,12 @@ let `class` = "keyword"   or contains nil (no value) to indicate that a value is missing.   Nil is roughly equivalent to `null` in other languages.   A question mark (?) after the type marks the value as optional of that type. -  +   If a type is not optional, it is guaranteed to have a value. -  +   Because Swift requires every property to have a type, even nil must be   explicitly stored as an Optional value. -  +   Optional<T> is an enum, with the cases .none (nil) and .some(T) (the value)   */ @@ -178,7 +178,7 @@ let someOptionalString4 = String?.none //nil   To access the value of an optional that has a value, use the postfix   operator !, which force-unwraps it. Force-unwrapping is like saying, "I   know that this optional definitely has a value, please give it to me." -  +   Trying to use ! to access a non-existent optional value triggers a   runtime error. Always make sure that an optional contains a non-nil   value before using ! to force-unwrap its value. @@ -194,7 +194,7 @@ if someOptionalString != nil {  // Swift supports "optional chaining," which means that you can call functions  //   or get properties of optional values and they are optionals of the appropriate type.  // You can even do this multiple times, hence the name "chaining." -     +  let empty = someOptionalString?.isEmpty // Bool?  // if-let structure - @@ -370,7 +370,7 @@ func say(_ message: String) {  }  say("Hello") -// Default parameters can be ommitted when calling the function. +// Default parameters can be omitted when calling the function.  func printParameters(requiredParameter r: Int, optionalParameter o: Int = 10) {      print("The required parameter was \(r) and the optional parameter was \(o)")  } @@ -443,7 +443,7 @@ func testGuard() {          return // guard statements MUST exit the scope that they are in.          // They generally use `return` or `throw`.      } -     +      print("number is \(aNumber)")  }  testGuard() @@ -564,7 +564,7 @@ enum Furniture {      case desk(height: Int)      // Associate with String and Int      case chair(String, Int) -     +      func description() -> String {          //either placement of let is acceptable          switch self { @@ -591,15 +591,15 @@ print(chair.description())    // "Chair of Foo with 40 cm"   - Define initializers to set up their initial state   - Be extended to expand their functionality beyond a default implementation   - Conform to protocols to provide standard functionality of a certain kind -  +   Classes have additional capabilities that structures don't have:   - Inheritance enables one class to inherit the characteristics of another.   - Type casting enables you to check and interpret the type of a class instance at runtime.   - Deinitializers enable an instance of a class to free up any resources it has assigned.   - Reference counting allows more than one reference to a class instance. -  +   Unless you need to use a class for one of these reasons, use a struct. -  +   Structures are value types, while classes are reference types.   */ @@ -607,7 +607,7 @@ print(chair.description())    // "Chair of Foo with 40 cm"  struct NamesTable {      let names: [String] -     +      // Custom subscript      subscript(index: Int) -> String {          return names[index] @@ -629,7 +629,7 @@ class Shape {  class Rect: Shape {      var sideLength: Int = 1 -     +      // Custom getter and setter property      var perimeter: Int {          get { @@ -640,16 +640,16 @@ class Rect: Shape {              sideLength = newValue / 4          }      } -     +      // Computed properties must be declared as `var`, you know, cause' they can change      var smallestSideLength: Int {          return self.sideLength - 1      } -     +      // Lazily load a property      // subShape remains nil (uninitialized) until getter called      lazy var subShape = Rect(sideLength: 4) -     +      // If you don't need a custom getter and setter,      // but still want to run code before and after getting or setting      // a property, you can use `willSet` and `didSet` @@ -659,19 +659,19 @@ class Rect: Shape {              print(someIdentifier)          }      } -     +      init(sideLength: Int) {          self.sideLength = sideLength          // always super.init last when init custom properties          super.init()      } -     +      func shrink() {          if sideLength > 0 {              sideLength -= 1          }      } -     +      override func getArea() -> Int {          return sideLength * sideLength      } @@ -703,13 +703,13 @@ class Circle: Shape {      override func getArea() -> Int {          return 3 * radius * radius      } -     +      // Place a question mark postfix after `init` is an optional init      // which can return nil      init?(radius: Int) {          self.radius = radius          super.init() -         +          if radius <= 0 {              return nil          } @@ -813,7 +813,7 @@ for _ in 0..<10 {   - Internal: Accessible and subclassible in the module it is declared in.   - Fileprivate: Accessible and subclassible in the file it is declared in.   - Private: Accessible and subclassible in the enclosing declaration (think inner classes/structs/enums) -  +   See more here: https://docs.swift.org/swift-book/LanguageGuide/AccessControl.html   */ @@ -878,11 +878,11 @@ extension Int {      var doubled: Int {          return self * 2      } -     +      func multipliedBy(num: Int) -> Int {          return num * self      } -     +      mutating func multiplyBy(num: Int) {          self *= num      } @@ -965,18 +965,18 @@ func fakeFetch(value: Int) throws -> String {      guard 7 == value else {          throw MyError.reallyBadValue(msg: "Some really bad value")      } -     +      return "test"  }  func testTryStuff() {      // assumes there will be no error thrown, otherwise a runtime exception is raised      let _ = try! fakeFetch(value: 7) -     +      // if an error is thrown, then it proceeds, but if the value is nil      // it also wraps every return value in an optional, even if its already optional      let _ = try? fakeFetch(value: 7) -     +      do {          // normal try operation that provides error handling via `catch` block          try fakeFetch(value: 1) | 
