Swift Solutions - Speaker Deck

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@subdigital

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Objec&ve(C

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[ ]

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2009

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BCSItem *item = [[BCSItem alloc] initWithIdentifier:@"id1"]; [item favorite];

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°□°#

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NSFileManager *fm = [NSFileManager defaultManager]; NSError *error = nil; BOOL result = [fm removeItemAtPath:path error:&error]; if (!result) { NSLog(“The error was: %@“, [error localizedDescription]); }

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Stockholm)Syndrome?

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Objec&ve(C*has*some*really*great*features.

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2014

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Swi$%is%diﬀerent.

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Swi$%is • clean'&'concise • memory'managed • safe • func3onal'(?)

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Why$do$we$need$a$safe$language?

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remember%goto%fail?

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no?

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hashOut.data = hashes + SSL_MD5_DIGEST_LEN; hashOut.length = SSL_SHA1_DIGEST_LEN; if ((err = SSLFreeBuffer(&hashCtx)) != 0) goto fail; if ((err = ReadyHash(&SSLHashSHA1, &hashCtx)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &clientRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail; if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0) goto fail; err = sslRawVerify(...); . . .

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hashOut.data = hashes + SSL_MD5_DIGEST_LEN; hashOut.length = SSL_SHA1_DIGEST_LEN; if ((err = SSLFreeBuffer(&hashCtx)) != 0) goto fail; if ((err = ReadyHash(&SSLHashSHA1, &hashCtx)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &clientRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail; <---------- if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0) goto fail; err = sslRawVerify(...); . . .

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Hidden&backdoor&to root$in$OS$X !! !!!h#ps:/ /truesecdev.wordpress.com/2015/04/09/hidden;backdoor;api;to;root;privileges;in;apple;os;x/

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! !!h#ps:/ /twi#er.com/tlrobinson/status/586202234582507520

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“Swi%&Sucks”

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“What&the&hell&were&they&thinking?”

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"Let’s'implement'our'own'open1 source'Swi4"

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Swi$%is%unique

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Idioma'c)Swi,

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We#are#s'll#learning#what#idioma'c# Swi4#is.

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So#let’s#take#a#look#at#some#cases#from#a#Swi1# viewpoint.

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Lazy%Proper+es%with%Closures

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func viewDidLoad() { super.viewDidLoad() let config = NSURLSessionConfiguration.defaultSessionConfiguration() session = NSURLSession( configuration: config, delegate: self, delegateQueue: nil) navigationItem.leftBarButtonItem = UIBarButtonItem( barButtonSystemItem: .Bookmarks, target: self, action: "bookmarks:") navigationItem.rightBarButtonItem = UIBarButtonItem( barButtonSystemItem: .Add, target: self, action: "add:") ... }

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@interface MyViewController () @property (nonatomic, strong) NSURLSessionConfiguration *configuration; @end - (NSURLSessionConfiguration *)configuration { if (_configuration == nil) { _configuration = [NSURLSessionConfiguration defaultSessionConfiguration]; } return _configuration; }

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lazy var configuration = NSURLSessionConfiguration.defaultSessionConfiguration()

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lazy var configuration = NSURLSessionConfiguration.defaultSessionConfiguration() lazy var session = ...

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lazy var configuration = NSURLSessionConfiguration.defaultSessionConfiguration() lazy var session: NSURLSession = { }()

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lazy var configuration = NSURLSessionConfiguration.defaultSessionConfiguration() lazy var session: NSURLSession = { return NSURLSession(configuration: self.configuration, delegate: self, delegateQueue: nil) }() lazy var leftBarButtonItem: UIBarButtonItem = { return UIBarButtonItem( barButtonSystemItem: .Bookmarks, target: self, action: "bookmarks:") }() lazy var rightBarButtonItem: UIBarButtonItem = { return UIBarButtonItem( barButtonSystemItem: .Add, target: self, action: "add:") }()

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func viewDidLoad() { super.viewDidLoad() navigationItem.leftBarButtonItem = leftBarButtonItem navigationItem.rightBarButtonItem = rightBarButtonItem }

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Returning)errors

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var error: NSError? = nil let object = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &error )

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class func JSONObjectWithData(data: NSData, options: NSJSONReadingOptions, error: NSErrorPointer) -> AnyObject

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func JSONObjectWithData( data: NSData, options: NSJSONReadingOptions = nil, ) -> (AnyObject?, NSError?)

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let result = JSONObjectWithData(data) result.0 // object? result.1 // error?

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let (object, error) = JSONObjectWithData(data) if let someObject = object { // can work with someObject } else { // error }

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func JSONObjectWithData( data: NSData, options: NSJSONReadingOptions = nil, ) -> (obj: AnyObject?, error: NSError?)

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let result = JSONObjectWithData(data) result.obj // object? result.error // error?

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Some%mes'if let'sucks

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Swi$%Pa(ern%Matching

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switch(result) { case (.Some(let x), nil): println("x's type is AnyObject") case (nil, .Some(let e)): println("e's type is NSError") default: }

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A"more"general"solu-on

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enum Result { case Value(T) case Error(NSError) }

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func JSONObjectWithData( data: NSData, options: NSJSONReadingOptions = nil ) -> Result

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func JSONObjectWithData( data: NSData, options: NSJSONReadingOptions = nil ) -> Result { .... if let error = parserError { return .Error(error) } else { return .Value(parsedObject) } }

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let result = JSONObjectWithData(data) switch(result) { case .Value(let obj): println("we parsed the object: \(obj)") case .Error(let error): println("error parsing json: \(error)") }

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(Side&Note:&Boxing¤tly&required) Hopefully)Apple)will)ﬁx)this)soon,)but)currently)you)need)to)box)the) T)value)for)this)to)work: class Box { var unbox: T init(_ value: T) { unbox = value } }

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enum Result { case Value(Box) case Error(NSError) } switch result { case .Value(let box): let val = box.unbox ... }

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More%on%Result%later...

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Map$/$Reduce

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struct Item { let name: String let price: Double let taxable: Bool }

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Given&a&Shopping&cart&full&of&items... let shoppingCart = [ Item(name: "Apples", price: 0.67, taxable: false), Item(name: "Bananas", price: 1.87, taxable: false), Item(name: "Beer", price: 6.99, taxable: true), Item(name: "Candy", price: 4.00, taxable: true), Item(name: "Ice Cream", price: 6.00, taxable: true) ]

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Compute(the(amount(of(tax(you( have(to(pay...

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let TaxRate = 0.0825

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let TaxRate = 0.0825 var tax = 0.0

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let TaxRate = 0.0825 var tax = 0.0 for item in shoppingCart { } println(tax)

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let TaxRate = 0.0825 var tax = 0.0 for item in shoppingCart { if item.taxable { } } println(tax)

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let TaxRate = 0.0825 var tax = 0.0 for item in shoppingCart { if item.taxable { tax += item.price * TaxRate } } println(tax)

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How$can$we$express$this$in$terms$of$ map,$filter,$and$reduce?

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map

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func map( source: C, transform: (C.Generator.Element) -> T) -> [T]

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func map( source: S, transform: (S.Generator.Element) -> T) -> [T]

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let items = [1, 2, 3] map(items, { (item: Int) -> Int in return item * 2 })

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let items = [1, 2, 3] map(items, { (item) -> Int in return item * 2 })

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let items = [1, 2, 3] map(items, { item in return item * 2 })

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map(items, { return $0 * 2 })

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map(items, { $0 * 2 })

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map(items) { $0 * 2 }

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[1,2,3].map { $0 * 2 }

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[1,2,3].map { $0 * 2 } // => [2, 4, 6]

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filter

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func filter( source: S, includeElement: (S.Generator.Element) -> Bool) -> [S.Generator.Element]

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[1,2,3].filter { $0 % 2 == 0 }

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[1,2,3].filter { $0 % 2 == 0 } // => [2]

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reduce

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func reduce( sequence: S, initial: U, combine: @noescape (U, S.Generator.Element) -> U) -> U

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[1,2,3].reduce(0) { (sum, n) in return sum + n }

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All#set?

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First&get&the&taxable&items let taxable = shoppingCart.filter { $0.taxable }

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Map$items$to$their$prices let taxable = shoppingCart.filter { $0.taxable } let taxableAmounts = taxable.map { $0.price }

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Reduce&to&a&single&value&(the&amount&of&tax) let taxable = shoppingCart.filter { $0.taxable } let taxableAmounts = taxable.map { $0.price } let tax = taxableAmounts.reduce(0) { (tax, itemPrice) in return tax + (itemPrice * TaxRate) }

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Can$simplify$the$reduce$block... let taxable = shoppingCart.filter { $0.taxable } let taxableAmounts = taxable.map { $0.price } let itemTaxes = taxable.map { $0 * TaxRate } let tax = itemTaxes.reduce(0) { (tax, itemTax) in return tax + (itemTax) }

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...into&an&exis+ng&func+on

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func +(lhs: Int, rhs: Int) -> Int { return lhs + rhs }

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Look$at$the$Shape$of$the$func/on... (T,T) -> U

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Look$at$the$Shape$of$the$func/on... !-> T

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(T,T)-> T

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(U,T)-> U

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Can$just$use$the$+$func-on... let taxable = shoppingCart.filter { $0.taxable } let taxableAmounts = taxable.map { $0.price } let itemTaxes = taxable.map { $0 * TaxRate } let tax = itemTaxes.reduce(0, combine: +)

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..."and"chain"them"together... let tax = shoppingCart .filter { $0.taxable } .map { $0.price } .map { $0 * TaxRate } .reduce(0, combine: +) println(tax) // 1.40

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Func%ons (no$interim$state,$no$loops,$no$condi1onals)

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func taxFunction(rate: Double)

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func taxFunction(rate: Double) -> ([Item]) -> Double {

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func taxFunction(rate: Double) -> ([Item]) -> Double { return { (items) in return items .filter { $0.taxable } .map { $0.price } .map { $0 * rate } .reduce(0, combine: +) } }

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let texasTax = taxFunction(0.0825) let tax = texasTax(items)

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Flat%Map

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We#know#what#map#is,#what#is#ﬂa1en? flatten([[5, 6], [4], [7, 8]]) -> [5,6,4,7,8]

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it#is#o&en#handy#to#ﬂa.en#before# mapping

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(ﬂat,&map)

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struct Person { var name: String var emails: [String] }

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"Give&me&a&list&of&all&email& addresses"

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people.map { $0.emails } ???

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There%is%no%ﬂa,en%func0on,%but%we%could% write%one... func flatten(array: [[T]) -> [T] { var result = [T]() for item in array { for subItem in item { result.append(subItem) } } return result }

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...ore%more%succinctly,%with%reduce: func flatten(array: [[T]) -> [T] { return array.reduce([], combine: +) }

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Yay!%Swi)%1.2%has%a%flatMap% func3on%:)

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[[1, 2], [3], [4, 5]].flatMap { $0 } // -> [1, 2, 3, 4, 5]

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people.flatMap { $0.emails }

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ﬂatMap&for&Result&?

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enum Result { case Value(Box) case Error(NSError) func flatMap(next: T -> Result) -> Result { switch self { case .Value(let box): let val = box.unbox return next(val) case .Error(let err): return .Error(err) } } }

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func getValue() -> Result func convertToFloat(i: Int) -> Result func squareRoot(x: Float) -> Result

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getValue().flatMap(convertToFloat).flatMap(squareRoot)

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Dealing(with(Index(Paths

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Remember&sta*c&table&views&before& Storyboards?

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func tableView(tableView: UITableView, cellForRowAtIndexPath: NSIndexPath) -> UITableViewCell { if indexPath.section == 0 { if indexPath.row == 0 { // } else { // ... } } else if indexPath.section == numberOfSectionsInTableView(tableView) - 1 { // ... } else { // ... } }

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func tableView(tableView: UITableView, cellForRowAtIndexPath: NSIndexPath) -> UITableViewCell { switch (indexPath) { case (0, 0): ... case (0, let row): ... case (let section, let row) where isLastSection(section): ... case (let section, let row): ... } }

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Enums&for&API&Endpoints

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Consider)an)API)with)some)paths: • /notifications • /users/:username • /catgories/:category_id/products/:product_id

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enum ApiEndpoints { case Notifications case UserProfile(String) case ProductDetail(Int, Int) }

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enum ApiEndpoints { case Notifications case UserProfile(String) case ProductDetail(Int, Int) var path: String { switch(self) { case .Notifications: return "/notifications" case .UserProfile(let username): return "/users/\(username.stringByAddingPercentEscapes...)" case .ProductDetail(let categoryId, let productId): return "/categories/\(categoryId)/products/\(productId)" } } }

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ApiClient.request(.UserProfile("subdigital")) { ... }

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Swi$%is%s'll%new

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"When&we&learn&a&new&programming& language,&we&may&need&[to]&discard& what&we&thought&it&should&be,&and& learn&what&it&will&be." —"a"Swi'"student

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thanks! @subdigital+•+@nsscreencast