Swift string concatenation, interception

Import UIKit

//swift string
in string//1>swift is a struct with higher performance
//2>nsstring is an OC object with slightly worse performance
//3> String supports direct traversal
of//4>swift provides a seamless conversion of string and nsstring let
str = "Hello World"

//Traversal string for
C in str.characters{
    Print (c)
}

//string concatenation
//concatenation between two strings let
str1 = "Hello" let

str2 = "World"

Let STR3 = str1 + str2

//concatenation of strings and other identifiers let
name = ' ZYF ' let-age

= '

height = 1.88 let

info = ' my Name is \ (name), my time is \ (age), my height is \ (height) "

//concatenation string, string formatting let
minent = 2 let

seconds = 8 let

timestring = String (format: "%02d:%02d", Arguments:[minent,seconds])

print (timestring)

// Intercept of the string let
urlstr = "www.zhengyanfeng.com"

//Convert the string type to NSString type let


header = (urlstr as NSString). SUBSTRING (to:3) let

BODY = (urlstr as NSString). Substring (With:nsrange (Location:4, length:12)) let

Afterbod y = (urlstr as NSString). SUBSTRING (from:17)