func checkSomething() {
 print("CheckPoint 1")
 doSomething()
 print("CheckPoint 4")
}
 
func doSomething() {
 print("CheckPoint 2")
 defer {
 print("Clean up here")
 }
 print("CheckPoint 3")
} 
checkSomething() // CheckPoint 1, CheckPoint 2, CheckPoint 3, Clean up here, CheckPoint 4

// 偽代碼
func writeSomething() {
 let file = OpenFile()
 let ioStatus = fetchIOStatus()
 guard ioStatus != "error" else {
  return
 }
 file.write()
 closeFile(file) 
}

// 偽代碼
func writeSomething() {
 let file = OpenFile()
 defer {
  closeFile(file)
 }
 let ioStatus = fetchIOStatus()
 guard ioStatus != "error" else {
  return
 }
 file.write()
}

var str = "Hello, playground"
func show() {
 print("這里是即將要推遲(但一定會(huì))執(zhí)行的代碼")
}
func test() {
 if str.characters.count >= 2 {
  print("跳出該方法的執(zhí)行")
  return
 }
 defer {
  show()
 }
}
test() // 輸出結(jié)果: 跳出該方法的執(zhí)行

var str = "Hello, playground"
func show() {
 print("這里是即將要推遲(但一定會(huì))執(zhí)行的代碼")
}
func test() {
 defer {
  show()
 }
 if str.characters.count >= 2 {
  print("跳出該方法的執(zhí)行")
  return
 }
}
test() // 輸出結(jié)果: 跳出該方法的執(zhí)行 這里是即將要推遲(但一定會(huì))執(zhí)行的代碼