替换部分过时函数

source/chapter2/03_Strings_and_Characters.md

@@ -150,11 +150,11 @@ let yenSign: Character = "¥"
 <a name="counting_characters"></a>
 ## 计算字符数量 (Counting Characters)
 
-通过调用全局`countElements`函数，并将字符串作为参数进行传递，可以获取该字符串的字符数量。
+通过调用全局`count(_:)`函数，并将字符串作为参数进行传递，可以获取该字符串的字符数量。
 
 ```swift
 let unusualMenagerie = "Koala 🐨, Snail 🐌, Penguin 🐧, Dromedary 🐪"
-println("unusualMenagerie has \(countElements(unusualMenagerie)) characters")
+println("unusualMenagerie has \(count(unusualMenagerie)) characters")
 // 打印输出："unusualMenagerie has 40 characters"
 ```
 

source/chapter2/06_Functions.md

@@ -116,7 +116,7 @@ sayGoodbye("Dave")
 ```swift
 func printAndCount(stringToPrint: String) -> Int {
     println(stringToPrint)
-    return countElements(stringToPrint)
+    return count(stringToPrint)
 }
 func printWithoutCounting(stringToPrint: String) {
     printAndCount(stringToPrint)
@@ -348,7 +348,7 @@ arithmeticMean(3, 8, 19)
 
 ```swift
 func alignRight(var string: String, count: Int, pad: Character) -> String {
-    let amountToPad = count - countElements(string)
+    let amountToPad = count - count(string)
     if amountToPad < 1 {
         return string
     }