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authorC. Bess <cbess@quantumquinn.com>2014-10-17 21:22:28 -0500
committerC. Bess <cbess@quantumquinn.com>2014-10-17 21:22:28 -0500
commit679d7098f2fe663b62e7a7e328369b760f94195c (patch)
tree06c3ac78c649f95d18c284ff7b20db0c9df10366
parent923a8ed99b1648cc2ece83660ed263492c332afe (diff)
- update examples
- further explain Optional types - add build config example - explain array/dictionary mutability - expand tuple example
-rw-r--r--swift.html.markdown56
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