Swift 1.2 langauge changes

Swift1Point2.swift

import Foundation

/*
    Improved Optional Binding: goodbye pyramid of doom
    Code and note extracted from: http://nshipster.com/swift-1.2/ (slightly modified)
*/

// Before Swift 1.2
let a = "10".toInt()
let b = "5".toInt()
let c = "3".toInt()

if let a = a {
    if let b = b {
        if let c = c {
            if c != 0 {
                println("(a + b) / c = \((a + b) / c)")
            }
        }
    }
}

// Swift 1.2
let x = "50".toInt()
let y = "5".toInt()
let z = "9".toInt()

if let x = x, y = y, z = z where c != 0 {
    println("(x - y) / z = \((x - y) / z)")
}

// Note: Each binding is evaluated in turn, stopping if any of the attempted bindings is nil.
// Only after all the optional bindings are successful is the wehre clause checked.

// Later binding expressions can reference earlier bindings
func intoSpanish(number: Int) -> String? {
    var spanish: String?
    if (number <= 50) {
        spanish = "Todo bien!"
    }
    return spanish;
}

if let x = x, translation = intoSpanish(x) {
    println(translation)
}

// Support a single leading boolean condition
let name = "Jorge"
let nationality = "Argentina"
if count(name) > 4 && contains(["Argentina", "Mexico", "Peru", "Bolivia"], nationality),
    let translation = intoSpanish(50) where !isEmpty(translation) {
        println("Localized: \(translation)")
}



/*
    Forced Failable Conversion with as!
*/

class SocialAccount {
    let accountName: String
    
    init(accountName: String) {
        self.accountName = accountName
    }
}

class TwitterAccount: SocialAccount {
    let fullName: String
    
    init(accountName:String, fullName: String) {
        self.fullName = fullName
        super.init(accountName: accountName)
    }
}

class FacebookAccount: SocialAccount {
    let isPage: Bool
    
    init(accountName: String, isPage: Bool) {
        self.isPage = isPage
        super.init(accountName: accountName)
    }
}

let account1: SocialAccount = TwitterAccount(accountName: "@vancity", fullName: "Vancouver")
let twitterAccount = account1 as! TwitterAccount
// Runtime error!
// let facebookAccount = account1 as! FacebookAccount

let account2: SocialAccount = FacebookAccount(accountName: "Alex", isPage: false)
if let facebookAccount = account2 as? FacebookAccount {
    print("FB account \(facebookAccount.accountName). Is it a page? \(facebookAccount.isPage)")
}

// as is used for upcast, type annotation and bridging conversion, checked at compile time
func out(s: String) {
    println(s)
}

let ns: NSString = "Apple Watch"
// Note: implicit converstion from bridged Objective-C classes to their corresponding
// Swift value types have been removed. (NSString->String, NSArray->Array, NSDictionary->Dictionary)
//out(ns) // No longer works
// Bridging conversion
out(ns as String)



/*
    New Collection Type: Set
*/

var team: Set<String> = []
team.insert("George")
team.insert("Peter")
team.insert("Greg")
team.insert("Alex")
team.insert("Peter")
println("Team has \(team.count) members");

// Some Set operations
// Code from: http://airspeedvelocity.net/2015/02/11/changes-to-the-swift-standard-library-in-1-2-beta-1/
let alphabets = Set("abcdefghijklmnopqrstuvwxyz")
println("There are \(alphabets.count) alphabets")
let consonants = alphabets.subtract("aeiou")
println("There are \(consonants.count) consonants")
consonants.isSubsetOf("abcdefghijklmnopqrstuvwxyz") // true

// Creating a new set
let newTeam = team.union(["Nancy", "Fernando"])
println("Old team has \(team.count) members");
println("New team has \(newTeam.count) members");
// Mutating the existing set
team.unionInPlace(["Nancy", "Fernando"])
team.contains("Nancy") // true
team.subtractInPlace(["Fernando"])
team.contains("Fernando") // false



/*
    Constants: Deferred initialization of let constants
*/

// With Swift 1.2, this is possible
// Unfortunately there is a known issue with the new let behavior not working in a global scope
// rdar://19770775
/*let englishSpeaking = false
let myName: String
if englishSpeaking {
    myName = "George"
} else {
    myName = "Jorge"
}
println("My name is \(myName).")*/

// Workaround
func myName(#spanish: Bool) -> String {
    let myName: String
    if spanish {
        myName = "Jorge"
    } else {
        myName = "George"
    }
    return myName
}
println("My name is \(myName(spanish: true))")



/*
    Other Swift 1.2 related writings:
    - http://adcdownload.apple.com//Developer_Tools/Xcode_6.3_beta_2/Xcode_6.3_beta_2_Release_Notes.pdf
    - https://developer.apple.com/swift/blog/?id=22
    - http://www.raywenderlich.com/95181/whats-new-in-swift-1-2
*/