定義字符串

let opratoin : String="ddffcc"

遍歷字符串

for c in opratoin.characters{

print(c)

}

字符串的拼接

let str1 ="哥"

let str2 ="didi "

var str3 ="aaa"

str3 = str1 + str2

字符串和其他字符之間的拼接

let name ="why"

let age =18

let height =1.88

let info ="my name is\(name) ,my age is\(age) ,my height is\(height)"

拼接字符串字符串的格式化

let min =2

let second =8

let timeStr =String(format:"%d:%d", [min,second]);

//字符串的截取

let urlString ="www.520.it.com"

將string轉換NSString

let header = (urlString as NSString).substring(to:3)

let middle = (urlString as NSString).substring(with:NSMakeRange(4,4))

let footer = (urlString as NSString).substring(from:10)