Statically-typed Swifty APIs

Statically-typed Swifty APIs Radek Pietruszewski @radexp • radex.io

@radexp • radex.io Dynamic vs static

@radexp • radex.io Modern static typing

@radexp • radex.io

@radexp • radex.io NSUserDefaults Case study

@radexp • radex.io NSUserDefaults.standardUserDefaults() .stringForKey("color") NSUserDefaults.standardUserDefaults() .setObject(NSDate(), forKey: "updatedAt")

@radexp • radex.io let Defaults = NSUserDefaults.standardUserDefaults() Defaults.integer(forKey: "launchCount") #Courage

@radexp • radex.io Defaults.integer(forKey: "launchCount") Defaults.set("red", forKey: "color") let dictionary
= ["launchCount": 10] dictionary["launchCount"] dictionary["color"] = "red"

@radexp • radex.io extension UserDefaults { subscript(key: String) -> AnyObject?
{ get { return object(forKey: key) } set { set(newValue, forKey: key) } } } Defaults["color"] Defaults["color"] = "red"

@radexp • radex.io Defaults["color"] // AnyObject?

@radexp • radex.io extension UserDefaults { subscript(key: String) -> Proxy
{ return Proxy(self, key) } }

@radexp • radex.io class Proxy { var string: String? {
return defaults.string(forKey: key) } var int: Int { return defaults.integer(forKey: key) } }

@radexp • radex.io Defaults["color"].string Defaults["launchCount"].int

@radexp • radex.io extension UserDefaults { subscript(key: String) -> Any?
{ set { if let v = newValue as? String { set(v, forKey: key) } else if let v = newValue as? Int { set(v, forKey: key) } } } }

@radexp • radex.io Common use cases

@radexp • radex.io Defaults["launchCount"] = Defaults["launchCount"].intValue + 1

@radexp • radex.io Defaults["launchCount"] += 1

@radexp • radex.io func += (proxy: UserDefaults.Proxy, b: Int) {
let a = proxy.defaults[proxy.key].intValue proxy.defaults[proxy.key] = a + b }

@radexp • radex.io postfix func ++ (proxy: UserDefaults.Proxy) { proxy
+= 1 }

@radexp • radex.io Defaults["launchCount"]++

@radexp • radex.io let defaults = NSUserDefaults.standardUserDefaults() defaults.setInteger( defaults.integerForKey("launchCount") +
1, forKey: "launchCount")

@radexp • radex.io Initial results

@radexp • radex.io Defaults["color"].string Defaults["launchCount"].int ?? 0 Defaults["launchCount"].intValue

@radexp • radex.io Defaults["color"] = "red" Defaults["totalTime"] += 3600

@radexp • radex.io But is this really Swifty?

@radexp • radex.io Defaults["color"] = "red"

@radexp • radex.io Defaults["color"] = "red" Defaults["colour"].string // => nil

@radexp • radex.io Defaults["deadline"] = Date.distantFuture Defaults["deadline"].data // => nil

@radexp • radex.io Defaults["deadline"] = Data() Defaults["deadline"].date // => nil

@radexp • radex.io Defaults["magic"] = 3.14 Defaults["magic"] += 10 Defaults["magic"]
// => 13

@radexp • radex.io Happens all the time!

@radexp • radex.io Fast feedback

@radexp • radex.io Refactoring

@radexp • radex.io The power of static typing

@radexp • radex.io let colorKey = "color"

@radexp • radex.io class DefaultsKey<ValueType> { let key: String }

@radexp • radex.io class DefaultsKey<ValueType> { let key: String }
let colorKey = DefaultsKey<String?>("color")

@radexp • radex.io let colorKey = DefaultsKey<String?>("color") extension UserDefaults {
subscript(key: DefaultsKey<String?>) -> String? { get { return string(forKey: key.key) } set { set(newValue, forKey: key.key) } } }

@radexp • radex.io Defaults[colorKey] = "green" Defaults[colorKey] // => "green"
: String? let colorKey = DefaultsKey<String?>("color")

@radexp • radex.io Subscripts are awesome

@radexp • radex.io var array = [1, 2, 3] array.first!
+= 10

@radexp • radex.io var array = [1, 2, 3] array[0]
+= 10 array // => [11, 2, 3]

@radexp • radex.io subscript(...) -> ... { get { ...
} set { ... } }

@radexp • radex.io array[0] += 10

@radexp • radex.io var temp = array[0] temp += 10
array[0] = temp

@radexp • radex.io Defaults[launchCountKey] += 1 Defaults[volumeKey] -= 0.1 Defaults[favoriteColorsKey].append("green")
Defaults[stringKey] += "… can be extended!"

@radexp • radex.io Defaults["color"] Defaults[Keys.color]

@radexp • radex.io Implicit member expressions

@radexp • radex.io turn(Direction.left) turn(.left)

@radexp • radex.io CGRect.zero -> .zero

@radexp • radex.io DefaultsKey.color -> .color

@radexp • radex.io extension DefaultsKeys { static let color =
DefaultsKey<String>("color") }

DefaultsKey<String>("color") } Defaults[.color] = "red"

@radexp • radex.io Defaults[.color] = "red"

@radexp • radex.io let key = DefaultsKey<[String]>("colors") Defaults[key].append("red") let red
= Defaults[key][0]

DefaultsKey<NSColor?>("color") } Defaults[.color] // => nil Defaults[.color] = .white Defaults[.color] // => w 1.0, a 1.0 Defaults[.color]?.whiteComponent // => 1.0

@radexp • radex.io Result: SwiftyUserDefaults

@radexp • radex.io extension DefaultsKeys { static let username =
DefaultsKey<String?>("username") static let launchCount = DefaultsKey<Int>("launchCount") static let libraries = DefaultsKey<[String]>("libraries") static let color = DefaultsKey<NSColor?>("color") }

@radexp • radex.io Defaults[.username] Defaults[.username] = "radex" Defaults[.launchCount] // Int,
defaults to 0

@radexp • radex.io Defaults[.launchCount] += 1 Defaults[.volume] -= 0.1 Defaults[.strings]
+= "… can be extended!"

@radexp • radex.io Defaults[.libraries].append("SwiftyUserDefaults") Defaults[.libraries][0] += " 2.0"

@radexp • radex.io Defaults[.color] = .white Defaults[.color]?.whiteComponent // => 1.0

@radexp • radex.io Static typing doesn't hurt in Swift

@radexp • radex.io Small price to opt in

@radexp • radex.io Free gifts from the compiler

@radexp • radex.io Compile-time checks

@radexp • radex.io Autocompletion

@radexp • radex.io Inferred types

@radexp • radex.io Plays nicely with value types

@radexp • radex.io Swifty APIs use static typing

@radexp • radex.io Modern type systems are nice

@radexp • radex.io github.com/radex/ SwiftyUserDefaults

Statically-typed Swifty APIs

Statically-typed Swifty APIs

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