1. 字符串定义
var s = "aaaaaa"
// 两个字符串均为空并等价。var emptyString = "" var anotherEmptyString = String()
字符串字面量可以包含以下特殊字符：转义字符 \0 (空字符)、 \\ (反斜线)、 \t (水平制表符)、 \n (换行符)、 \r (回车符)、 \" (双引号)、 \' (单引号)。
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单字节 Unicode 标量，写成
\xnn，其中nn为两位十六进制数。双字节 Unicode 标量，写成
\unnnn，其中nnnn为四位十六进制数。四字节 Unicode 标量，写成
\Unnnnnnnn，其中nnnnnnnn为八位十六进制数。
2. 字符串拼接
//字符串拼接var x = "x"var y = "y"var z = x + yvar m = z + "m"var n = "n"n += m//使用\()完成字符串的插值var result = "\(x)==\(y)==\(z)==\(m)==\(n)"println(result)let plus1 = s1 + c1
3. 字符串遍历
var myString = "This is a string"for character in myString{ println(character)} 4. 字符个数统计
var myString = "Here is my string, lets count the characters!"println(count(myString))
5. 字符串比较 & 是否包含前后缀
var check1:String = "Swift is good!"var check2:String = "Swift is good!"//字符串是否相等if check1 == check2 { println("check1 = check2")} else { println("check1 != check2")}//是否包含前缀var preCheck = "Swift"if check1.hasPrefix(preCheck) { println("包含前缀")}//是否包含后缀var sufCheck = "good!"if check1.hasSuffix(sufCheck) { println("包含后缀")} 6. 大小写转换
let myString = "Wait a moment, please."let newString = myString.uppercaseStringlet myString = "Wait a moment, please."let newString = myString.lowercaseString
7. 字符串是否包含其他字符串
var myString = "This is a string test"if myString.rangeOfString("test") { println("exists")} 8. 字符串截取
//截取字符串的标识位从1开始计数let myString = "ABCDEFGHI"//1.从目标标识位后一个字符开始截取余下的字符串let mySubstring = (myString.substringFromIndex(2))println(mySubstring) let mySubstring2 = (myString.substringToIndex(4))println(mySubstring2)
9. 字符串去空格
var myString = " Let's trim the whitespace " var newString = myString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
10. 字符串分割为字符串数组
//单一分隔符:只有一种分割符var myString = "Berlin, Paris, New York, San Francisco"//1.隐式定义字符串数组var myArray = myString.componentsSeparatedByString(",")//2.显示定义字符串数组var myArray2 : String[] = myString.componentsSeparatedByString(", ")for em in myArray2 { print(em) }//多重分割符:有2个或两个以上分隔符var myString2 = "One-Two-Three-1 2 3"var array2:String[] = myString2.componentsSeparatedByCharactersInSet(NSCharacterSet (charactersInString: "- "))//["One", "Two", "Three", "1", "2", "3"] 11.字符串转换为NSData
let myString = "String to encode"let string: NSString = myStringlet data = string.dataUsingEncoding(NSUTF8StringEncoding)