diff options
| -rw-r--r-- | swift.html.markdown | 56 |
1 files changed, 52 insertions, 4 deletions
diff --git a/swift.html.markdown b/swift.html.markdown index ffe6cac2..005e511c 100644 --- a/swift.html.markdown +++ b/swift.html.markdown @@ -27,6 +27,9 @@ import UIKit println("Hello, world") +// variables (var) value can change after being set +// constants (let) value can NOT be changed after being set + var myVariable = 42 let øπΩ = "value" // unicode variable names let π = 3.1415926 @@ -38,7 +41,29 @@ let intValue = 0007 // 7 let largeIntValue = 77_000 // 77000 let label = "some text " + String(myVariable) // Casting let piText = "Pi = \(π), Pi 2 = \(π * 2)" // String interpolation + +// Build Specific values +// uses -D build configuration +#if false + println("Not printed") + let buildValue = 3 +#else + let buildValue = 7 +#endif +println("Build value: \(buildValue)") // Build value: 7 + +/* + Optionals are a Swift language feature that allows you to store a `Some` or + `None` 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. +*/ var someOptionalString: String? = "optional" // Can be nil +// same as above, but ? is a postfix operator (syntax candy) +var someOptionalString2: Optional<String> = "optional" if someOptionalString != nil { // I am not nil @@ -50,11 +75,23 @@ if someOptionalString != nil { } someOptionalString = nil -if let someStringConstant = someOptionalString { - // has Some value +// implicitly unwrapped optional +var unwrappedString: String! = "Value is expected." +// same as above, but ! is a postfix operator (more syntax candy) +var unwrappedString2: ImplicitlyUnwrappedOptional<String> = "Value is expected." + +if let someOptionalStringConstant = someOptionalString { + // has `Some` value, non-nil + if !someOptionalStringConstant.hasPrefix("ok") { + // does not have the prefix + } } +// Swift has support for storing a value of any type. // AnyObject == id +// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc) +var anyObjectVar: AnyObject = 7 +anyObjectVar = "Changed value to a string, not good practice, but possible." /* Comment here @@ -67,10 +104,17 @@ Comment here // MARK: Collections // +/* + 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 var shoppingList = ["catfish", "water", "lemons"] shoppingList[1] = "bottle of water" -let emptyArray = [String]() +let emptyArray = [String]() // immutable +var emptyMutableArray = [String]() // mutable + // Dictionary var occupations = [ @@ -78,7 +122,8 @@ var occupations = [ "kaylee": "Mechanic" ] occupations["Jayne"] = "Public Relations" -let emptyDictionary = [String: Float]() +let emptyDictionary = [String: Float]() // immutable +var emptyMutableDictionary = [String: Float]() // mutable // @@ -162,6 +207,9 @@ func getGasPrices() -> (Double, Double, Double) { } let pricesTuple = getGasPrices() let price = pricesTuple.2 // 3.79 +// Ignore Tuple (or other) values by using _ (underscore) +let (_, price1, _) = pricesTuple // price1 == 3.69 +println(price1 == pricesTuple.1) // true println("Gas price: \(price)") // Variadic Args |