diff options
| -rw-r--r-- | swift.html.markdown | 68 |
1 files changed, 36 insertions, 32 deletions
diff --git a/swift.html.markdown b/swift.html.markdown index 2fc92da7..b6554dc6 100644 --- a/swift.html.markdown +++ b/swift.html.markdown @@ -7,6 +7,7 @@ contributors: - ["Anthony Nguyen", "http://github.com/anthonyn60"] - ["Clayton Walker", "https://github.com/cwalk"] - ["Fernando Valverde", "http://visualcosita.xyz"] + - ["Alexey Nazaroff", "https://github.com/rogaven"] filename: learnswift.swift --- @@ -104,10 +105,12 @@ if let someOptionalStringConstant = someOptionalString { } // Swift has support for storing a value of any type. -// AnyObject == id -// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc.) -var anyObjectVar: AnyObject = 7 -anyObjectVar = "Changed value to a string, not good practice, but possible." +// For that purposes there is two keywords: `Any` and `AnyObject` +// `AnyObject` == `id` from Objective-C +// `Any` – also works with any scalar values (Class, Int, struct, etc.) +var anyVar: Any = 7 +anyVar = "Changed value to a string, not good practice, but possible." +let anyObjectVar: AnyObject = Int(1) as NSNumber /* Comment here @@ -151,11 +154,11 @@ var explicitEmptyMutableDictionary: [String: Float] = [:] // same as above // MARK: Control Flow // -// Condition statements support "where" clauses, which can be used +// Condition statements support "," (comma) clauses, which can be used // to help provide conditions on optional values. -// Both the assignment and the "where" clause must pass. +// Both the assignment and the "," clause must pass. let someNumber = Optional<Int>(7) -if let num = someNumber where num > 3 { +if let num = someNumber, num > 3 { print("num is greater than 3") } @@ -230,13 +233,13 @@ A greet operation func greet(name: String, day: String) -> String { return "Hello \(name), today is \(day)." } -greet("Bob", day: "Tuesday") +greet(name: "Bob", day: "Tuesday") // similar to above except for the function parameter behaviors -func greet2(requiredName requiredName: String, externalParamName localParamName: String) -> String { - return "Hello \(requiredName), the day is \(localParamName)" +func greet2(name: String, externalParamName localParamName: String) -> String { + return "Hello \(name), the day is \(localParamName)" } -greet2(requiredName: "John", externalParamName: "Sunday") +greet2(name: "John", externalParamName: "Sunday") // Function that returns multiple items in a tuple func getGasPrices() -> (Double, Double, Double) { @@ -279,7 +282,7 @@ func setup(numbers: Int...) { } // Passing and returning functions -func makeIncrementer() -> (Int -> Int) { +func makeIncrementer() -> ((Int) -> Int) { func addOne(number: Int) -> Int { return 1 + number } @@ -289,14 +292,14 @@ var increment = makeIncrementer() increment(7) // pass by ref -func swapTwoInts(inout a: Int, inout b: Int) { +func swapTwoInts(a: inout Int, b: inout Int) { let tempA = a a = b b = tempA } var someIntA = 7 var someIntB = 3 -swapTwoInts(&someIntA, b: &someIntB) +swapTwoInts(a: &someIntA, b: &someIntB) print(someIntB) // 7 @@ -324,7 +327,7 @@ numbers = numbers.map({ number in 3 * number }) print(numbers) // [3, 6, 18] // Trailing closure -numbers = numbers.sort { $0 > $1 } +numbers = numbers.sorted { $0 > $1 } print(numbers) // [18, 6, 3] @@ -351,8 +354,8 @@ print("Name is \(name)") // Name is Them // MARK: Error Handling // -// The `ErrorType` protocol is used when throwing errors to catch -enum MyError: ErrorType { +// The `Error` protocol is used when throwing errors to catch +enum MyError: Error { case BadValue(msg: String) case ReallyBadValue(msg: String) } @@ -368,15 +371,15 @@ func fakeFetch(value: Int) throws -> String { func testTryStuff() { // assumes there will be no error thrown, otherwise a runtime exception is raised - let _ = try! fakeFetch(7) + 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(7) + let _ = try? fakeFetch(value: 7) do { // normal try operation that provides error handling via `catch` block - try fakeFetch(1) + try fakeFetch(value: 1) } catch MyError.BadValue(let msg) { print("Error message: \(msg)") } catch { @@ -570,10 +573,11 @@ protocol ShapeGenerator { } // Protocols declared with @objc allow optional functions, -// which allow you to check for conformance +// which allow you to check for conformance. These functions must be +// marked with @objc also. @objc protocol TransformShape { - optional func reshape() - optional func canReshape() -> Bool + @objc optional func reshape() + @objc optional func canReshape() -> Bool } class MyShape: Rect { @@ -585,7 +589,7 @@ class MyShape: Rect { // Place a question mark after an optional property, method, or // subscript to gracefully ignore a nil value and return nil // instead of throwing a runtime error ("optional chaining"). - if let reshape = self.delegate?.canReshape?() where reshape { + if let reshape = self.delegate?.canReshape?(), reshape { // test for delegate then for method self.delegate?.reshape?() } @@ -620,20 +624,20 @@ extension Int { } print(7.customProperty) // "This is 7" -print(14.multiplyBy(3)) // 42 +print(14.multiplyBy(num: 3)) // 42 // Generics: Similar to Java and C#. Use the `where` keyword to specify the // requirements of the generics. -func findIndex<T: Equatable>(array: [T], _ valueToFind: T) -> Int? { - for (index, value) in array.enumerate() { +func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? { + for (index, value) in array.enumerated() { if value == valueToFind { return index } } return nil } -let foundAtIndex = findIndex([1, 2, 3, 4], 3) +let foundAtIndex = findIndex(array: [1, 2, 3, 4], valueToFind: 3) print(foundAtIndex == 2) // true // Operators: @@ -641,10 +645,10 @@ print(foundAtIndex == 2) // true // / = - + * % < > ! & | ^ . ~ // or // Unicode math, symbol, arrow, dingbat, and line/box drawing characters. -prefix operator !!! {} +prefix operator !!! // A prefix operator that triples the side length when used -prefix func !!! (inout shape: Square) -> Square { +prefix func !!! (shape: inout Square) -> Square { shape.sideLength *= 3 return shape } @@ -657,8 +661,8 @@ print(mySquare.sideLength) // 4 print(mySquare.sideLength) // 12 // Operators can also be generics -infix operator <-> {} -func <-><T: Equatable> (inout a: T, inout b: T) { +infix operator <-> +func <-><T: Equatable> (a: inout T, b: inout T) { let c = a a = b b = c |