[IOS] URL encoding and decoding

1. First look at what is URL encoding (string with%22 similar to this)

NSString *str = @ "http://m.tuniu.com/api/home/data/index/c/%7B%22v%22%3A%227.1.0%22%2C%22ct%22%3A20%2C%22dt%22% 3a1%2c%22p%22%3a11210%2c%22cc%22%3a2500%7d/d/%7b%22clientmodel%22%3a%22honor+h30-l01%22%2c%22width%22%3a720%7d "

Decode the URL

decoding

NSString *str2 = [str stringbyremovingpercentencoding]; (iOS9.0 (including 9.0) use)

　　NSString *str2 = [str stringbyaddingpercentescapesusingencoding:nsutf8stringencoding]; (use below iOS9.0)

Encode the URL

Coding

NSString *STR3 = [str2 stringbyaddingpercentencodingwithallowedcharacters: [nscharacterset  Urlqueryallowedcharacterset]]; (iOS9.0 (including 9.0) use)

　　NSString *STR3 = [str2 stringbyaddingpercentescapesusingencoding:nsutf8stringencoding]; (use below iOS9.0)

[IOS] URL encoding and decoding