- update Swift examples

- update to upgrade to Swift 2.1
- code cleanup
This commit is contained in:
C. Bess 2015-11-09 18:09:48 -06:00
parent df0992d72c
commit 618f8f5bad

View File

@ -32,7 +32,7 @@ import UIKit
// In Swift 2, println and print were combined into one print method. Print automatically appends a new line. // In Swift 2, println and print were combined into one print method. Print automatically appends a new line.
print("Hello, world") // println is now print print("Hello, world") // println is now print
print("Hello, world", appendNewLine: false) // printing without appending a newline print("Hello, world", terminator: "") // printing without appending a newline
// variables (var) value can change after being set // variables (var) value can change after being set
// constants (let) value can NOT be changed after being set // constants (let) value can NOT be changed after being set
@ -60,14 +60,14 @@ let piText = "Pi = \(π), Pi 2 = \(π * 2)" // String interpolation
print("Build value: \(buildValue)") // Build value: 7 print("Build value: \(buildValue)") // Build value: 7
/* /*
Optionals are a Swift language feature that either contains a value, Optionals are a Swift language feature that either contains a value,
or contains nil (no value) to indicate that a value is missing. or contains nil (no value) to indicate that a value is missing.
A question mark (?) after the type marks the value as optional. A question mark (?) after the type marks the value as optional.
Because Swift requires every property to have a value, even nil must be Because Swift requires every property to have a value, even nil must be
explicitly stored as an Optional value. explicitly stored as an Optional value.
Optional<T> is an enum. Optional<T> is an enum.
*/ */
var someOptionalString: String? = "optional" // Can be nil var someOptionalString: String? = "optional" // Can be nil
// same as above, but ? is a postfix operator (syntax candy) // same as above, but ? is a postfix operator (syntax candy)
@ -84,9 +84,9 @@ if someOptionalString != nil {
someOptionalString = nil someOptionalString = nil
/* /*
Trying to use ! to access a non-existent optional value triggers a runtime 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 error. Always make sure that an optional contains a non-nil value before
using ! to force-unwrap its value. using ! to force-unwrap its value.
*/ */
// implicitly unwrapped optional // implicitly unwrapped optional
@ -120,8 +120,8 @@ anyObjectVar = "Changed value to a string, not good practice, but possible."
// //
/* /*
Array and Dictionary types are structs. So `let` and `var` also indicate Array and Dictionary types are structs. So `let` and `var` also indicate
that they are mutable (var) or immutable (let) when declaring these types. that they are mutable (var) or immutable (let) when declaring these types.
*/ */
// Array // Array
@ -178,8 +178,8 @@ while i < 1000 {
i *= 2 i *= 2
} }
// do-while loop // repeat-while loop
do { repeat {
print("hello") print("hello")
} while 1 == 2 } while 1 == 2
@ -209,22 +209,22 @@ default: // required (in order to cover all possible input)
// Function with Swift header docs (format as reStructedText) // Function with Swift header docs (format as reStructedText)
/** /**
A greet operation A greet operation
- A bullet in docs - A bullet in docs
- Another bullet in the docs - Another bullet in the docs
:param: name A name :param: name A name
:param: day A day :param: day A day
:returns: A string containing the name and day value. :returns: A string containing the name and day value.
*/ */
func greet(name: String, day: String) -> String { func greet(name: String, day: String) -> String {
return "Hello \(name), today is \(day)." return "Hello \(name), today is \(day)."
} }
greet("Bob", "Tuesday") greet("Bob", day: "Tuesday")
// similar to above except for the function parameter behaviors // similar to above except for the function parameter behaviors
func greet2(#requiredName: String, externalParamName localParamName: String) -> String { func greet2(requiredName requiredName: String, externalParamName localParamName: String) -> String {
return "Hello \(requiredName), the day is \(localParamName)" return "Hello \(requiredName), the day is \(localParamName)"
} }
greet2(requiredName: "John", externalParamName: "Sunday") greet2(requiredName: "John", externalParamName: "Sunday")
@ -247,14 +247,14 @@ func getGasPrices2() -> (lowestPrice: Double, highestPrice: Double, midPrice: Do
let pricesTuple2 = getGasPrices2() let pricesTuple2 = getGasPrices2()
let price2 = pricesTuple2.lowestPrice let price2 = pricesTuple2.lowestPrice
let (_, price3, _) = pricesTuple2 let (_, price3, _) = pricesTuple2
println(pricesTuple2.highestPrice == pricesTuple2.1) // true print(pricesTuple2.highestPrice == pricesTuple2.1) // true
println("Highest gas price: \(pricesTuple2.highestPrice)") print("Highest gas price: \(pricesTuple2.highestPrice)")
// Variadic Args // Variadic Args
func setup(numbers: Int...) { func setup(numbers: Int...) {
// its an array // its an array
let number = numbers[0] let _ = numbers[0]
let argCount = numbers.count let _ = numbers.count
} }
// Passing and returning functions // Passing and returning functions
@ -275,7 +275,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
} }
var someIntA = 7 var someIntA = 7
var someIntB = 3 var someIntB = 3
swapTwoInts(&someIntA, &someIntB) swapTwoInts(&someIntA, b: &someIntB)
print(someIntB) // 7 print(someIntB) // 7
@ -303,23 +303,17 @@ numbers = numbers.map({ number in 3 * number })
print(numbers) // [3, 6, 18] print(numbers) // [3, 6, 18]
// Trailing closure // Trailing closure
numbers = sorted(numbers) { $0 > $1 } numbers = numbers.sort { $0 > $1 }
print(numbers) // [18, 6, 3] print(numbers) // [18, 6, 3]
// Super shorthand, since the < operator infers the types
numbers = sorted(numbers, < )
print(numbers) // [3, 6, 18]
// //
// MARK: Structures // MARK: Structures
// //
// Structures and classes have very similar capabilities // Structures and classes have very similar capabilities
struct NamesTable { struct NamesTable {
let names = [String]() let names: [String]
// Custom subscript // Custom subscript
subscript(index: Int) -> String { subscript(index: Int) -> String {
@ -472,9 +466,10 @@ enum Suit {
// when the variable is explicitly declared // when the variable is explicitly declared
var suitValue: Suit = .Hearts var suitValue: Suit = .Hearts
// Non-Integer enums require direct raw value assignments // String enums can have direct raw value assignments
// or their raw values will be derived from the Enum field
enum BookName: String { enum BookName: String {
case John = "John" case John
case Luke = "Luke" case Luke = "Luke"
} }
print("Name: \(BookName.John.rawValue)") print("Name: \(BookName.John.rawValue)")
@ -518,7 +513,7 @@ protocol ShapeGenerator {
// Protocols declared with @objc allow optional functions, // Protocols declared with @objc allow optional functions,
// which allow you to check for conformance // which allow you to check for conformance
@objc protocol TransformShape { @objc protocol TransformShape {
optional func reshaped() optional func reshape()
optional func canReshape() -> Bool optional func canReshape() -> Bool
} }
@ -531,9 +526,9 @@ class MyShape: Rect {
// Place a question mark after an optional property, method, or // Place a question mark after an optional property, method, or
// subscript to gracefully ignore a nil value and return nil // subscript to gracefully ignore a nil value and return nil
// instead of throwing a runtime error ("optional chaining"). // instead of throwing a runtime error ("optional chaining").
if let allow = self.delegate?.canReshape?() { if let reshape = self.delegate?.canReshape?() where reshape {
// test for delegate then for method // test for delegate then for method
self.delegate?.reshaped?() self.delegate?.reshape?()
} }
} }
} }
@ -546,7 +541,7 @@ class MyShape: Rect {
// `extension`s: Add extra functionality to an already existing type // `extension`s: Add extra functionality to an already existing type
// Square now "conforms" to the `Printable` protocol // Square now "conforms" to the `Printable` protocol
extension Square: Printable { extension Square: CustomStringConvertible {
var description: String { var description: String {
return "Area: \(self.getArea()) - ID: \(self.identifier)" return "Area: \(self.getArea()) - ID: \(self.identifier)"
} }
@ -571,8 +566,8 @@ print(14.multiplyBy(3)) // 42
// Generics: Similar to Java and C#. Use the `where` keyword to specify the // Generics: Similar to Java and C#. Use the `where` keyword to specify the
// requirements of the generics. // requirements of the generics.
func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? { func findIndex<T: Equatable>(array: [T], _ valueToFind: T) -> Int? {
for (index, value) in enumerate(array) { for (index, value) in array.enumerate() {
if value == valueToFind { if value == valueToFind {
return index return index
} }