Swift代码：
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/* this is also a comment,
but written over multiple lines */
/* multiline comments
/* can be nested! */
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// Swift variables are declared with "var"
// this is followed by a name, a type, and a value
var explicitDouble: Double = 70
// If the type is omitted, Swift will infer it from
// the variable\'s initial value
var implicitInteger = 70
var implicitDouble = 70.0
var 國 = "美國"
// Swift constants are declared with "let"
// followed by a name, a type, and a value
let numberOfBananas: Int = 10
// Like variables, if the type of a constant is omitted,
// Swift will infer it from the constant\'s value
let numberOfApples = 3
let numberOfOranges = 5
// Values of variables and constants can both be
// interpolated in strings as follows
let appleSummary = "I have \(numberOfApples) apples."
let fruitSummary = "I have \(numberOfApples + numberOfOranges) pieces of fruit."
// In "playgrounds", code can be placed in the global scope
println("Hello, world")
// This is an array variable
var fruits = ["mango", "kiwi", "avocado"]
// Example of an if statement; .isEmpty, .count
if fruits.isEmpty {
println("No fruits in my array.")
} else {
println("There are \(fruits.count) items in my array")
}
// Define a dictionary with four items:
// Each item has a person\'s name and age
let people = ["Anna": 67, "Beto": 8, "Jack": 33, "Sam": 25]
// Now we use Swift\'s flexible enumerator system
// to extract both values in a single loop
for (name, age) in people {
println("\(name) is \(age) years old.")
}
// Functions and methods are both declared with the
// "func" syntax, and the return type is specified with ->
func sayHello(personName: String) -> String {
let greeting = "Hello, " + personName + "!"
return greeting
}
// prints "Hello, Dilan!"
print(sayHello("Dilan"))
// Parameter names can be made external and required
// for calling.
// The external name can be the same as the parameter
// name by prefixing with an octothorpe (#)
// - or it can be defined separately.
func sayAge(#personName: String, personAge Age: Int) -> String {
let result = "\(personName) is \(Age) years old."
return result
}
// We can also specify the name of the parameter
print(sayAge(personName: "Dilan", personAge: 42))