- 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.
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
// 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
/*
Optionals are a Swift language feature that either contains a value,
or contains nil (no value) to indicate that a value is missing.
A question mark (?) after the type marks the value as optional.
Optionals are a Swift language feature that either contains a value,
or contains nil (no value) to indicate that a value is missing.
A question mark (?) after the type marks the value as optional.
Because Swift requires every property to have a value, even nil must be
explicitly stored as an Optional value.
Because Swift requires every property to have a value, even nil must be
explicitly stored as an Optional value.
Optional<T> is an enum.
Optional<T> is an enum.
*/
var someOptionalString: String? = "optional" // Can be nil
// same as above, but ? is a postfix operator (syntax candy)
@ -84,9 +84,9 @@ if someOptionalString != nil {
someOptionalString = nil
/*
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.
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.
*/
// 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
that they are mutable (var) or immutable (let) when declaring these types.
Array and Dictionary types are structs. So `let` and `var` also indicate
that they are mutable (var) or immutable (let) when declaring these types.
*/
// Array
@ -178,8 +178,8 @@ while i < 1000 {
i *= 2
}
// do-while loop
do {
// repeat-while loop
repeat {
print("hello")
} while 1 == 2
@ -209,22 +209,22 @@ default: // required (in order to cover all possible input)
// Function with Swift header docs (format as reStructedText)
/**
A greet operation
A greet operation
- A bullet in docs
- Another bullet in the docs
- A bullet in docs
- Another bullet in the docs
:param: name A name
:param: day A day
:returns: A string containing the name and day value.
:param: name A name
:param: day A day
:returns: A string containing the name and day value.
*/
func greet(name: String, day: String) -> String {
return "Hello \(name), today is \(day)."
}
greet("Bob", "Tuesday")
greet("Bob", day: "Tuesday")
// 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)"
}
greet2(requiredName: "John", externalParamName: "Sunday")
@ -247,14 +247,14 @@ func getGasPrices2() -> (lowestPrice: Double, highestPrice: Double, midPrice: Do
let pricesTuple2 = getGasPrices2()
let price2 = pricesTuple2.lowestPrice
let (_, price3, _) = pricesTuple2
println(pricesTuple2.highestPrice == pricesTuple2.1) // true
println("Highest gas price: \(pricesTuple2.highestPrice)")
print(pricesTuple2.highestPrice == pricesTuple2.1) // true
print("Highest gas price: \(pricesTuple2.highestPrice)")
// Variadic Args
func setup(numbers: Int...) {
// its an array
let number = numbers[0]
let argCount = numbers.count
let _ = numbers[0]
let _ = numbers.count
}
// Passing and returning functions
@ -275,7 +275,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
}
var someIntA = 7
var someIntB = 3
swapTwoInts(&someIntA, &someIntB)
swapTwoInts(&someIntA, b: &someIntB)
print(someIntB) // 7
@ -303,23 +303,17 @@ numbers = numbers.map({ number in 3 * number })
print(numbers) // [3, 6, 18]
// Trailing closure
numbers = sorted(numbers) { $0 > $1 }
numbers = numbers.sort { $0 > $1 }
print(numbers) // [18, 6, 3]
// Super shorthand, since the < operator infers the types
numbers = sorted(numbers, < )
print(numbers) // [3, 6, 18]
//
// MARK: Structures
//
// Structures and classes have very similar capabilities
struct NamesTable {
let names = [String]()
let names: [String]
// Custom subscript
subscript(index: Int) -> String {
@ -472,9 +466,10 @@ enum Suit {
// when the variable is explicitly declared
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 {
case John = "John"
case John
case Luke = "Luke"
}
print("Name: \(BookName.John.rawValue)")
@ -518,7 +513,7 @@ protocol ShapeGenerator {
// Protocols declared with @objc allow optional functions,
// which allow you to check for conformance
@objc protocol TransformShape {
optional func reshaped()
optional func reshape()
optional func canReshape() -> Bool
}
@ -531,9 +526,9 @@ 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 allow = self.delegate?.canReshape?() {
if let reshape = self.delegate?.canReshape?() where reshape {
// 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
// Square now "conforms" to the `Printable` protocol
extension Square: Printable {
extension Square: CustomStringConvertible {
var description: String {
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
// requirements of the generics.
func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
for (index, value) in enumerate(array) {
func findIndex<T: Equatable>(array: [T], _ valueToFind: T) -> Int? {
for (index, value) in array.enumerate() {
if value == valueToFind {
return index
}