{ (parameters) -> return type in
statements
}

reversedNames = names.sorted(by: { (s1: String, s2: String) -> Bool in return s1 > s2 } )

reversedNames = names.sorted(by: { s1, s2 in return s1 > s2 } )

reversedNames = names.sorted(by: { s1, s2 in s1 > s2 } )

reversedNames = names.sorted(by: { $0 > $1 } )

reversedNames = names.sorted(by: >)

reversedNames = names.sorted() { $0 > $1 }

reversedNames = names.sorted { $0 > $1 }

func makeIncrementer(forIncrement amount: Int) -> () -> Int {
 var runningTotal = 0
 func incrementer() -> Int {
 runningTotal += amount
 return runningTotal
 }
 return incrementer
}

let incrementByTen = makeIncrementer(forIncrement: 10)
incrementByTen()
// returns a value of 10
incrementByTen()
// returns a value of 20
incrementByTen()
// returns a value of 30

let alsoIncrementByTen = incrementByTen
alsoIncrementByTen()

//需要加@escaping的情况
var completionHandlers: [() -> Void] = []
func someFunctionWithEscapingClosure(completionHandler: @escaping () -> Void) {
 completionHandlers.append(completionHandler)
}
//直接在函数内调用传入的闭包则不需要@escaping
func someFunctionWithNonescapingClosure(closure: () -> Void) {
 closure()
}

// customersInLine is ["Alex", "Ewa", "Barry", "Daniella"]
func serve(customer customerProvider: () -> String) {
 print("Now serving \(customerProvider())!")
}
serve(customer: { customersInLine.remove(at: 0) } )
// Prints "Now serving Alex!"

// customersInLine is ["Ewa", "Barry", "Daniella"]
func serve(customer customerProvider: @autoclosure () -> String) {
 print("Now serving \(customerProvider())!")
}
serve(customer: customersInLine.remove(at: 0))
// Prints "Now serving Ewa!"