stringByAddingPercentEncodingWithAllowedCharacters

（1） 网络访问请求：中文空格字符编码/解码

stringByAddingPercentEscapesUsingEncoding(只对 `#%^{}[]|\"<> 加空格共14个字符编码，不包括”&?”等符号), ios9将淘汰，建议用stringByAddingPercentEncodingWithAllowedCharacters方法

URLFragmentAllowedCharacterSet  "#%<>[\]^`{|}

URLHostAllowedCharacterSet      "#%/<>?@\^`{|}

URLPasswordAllowedCharacterSet  "#%/:<>?@[\]^`{|}

URLPathAllowedCharacterSet      "#%;<>?[\]^`{|}

URLQueryAllowedCharacterSet     "#%<>[\]^`{|}

URLUserAllowedCharacterSet      "#%/:<>?@[\]^`

（2）网络访问请求：中文空格字符解码

stringByRemovingPercentEncoding  ----  xcode7可能会提示要将stringByAddingPercentEscapesUsingEncoding替换成此方法，要根据是否是解码来区分
*/
//代替stringByAddingPercentEscapesUsingEncoding

let customAllowedSet =  NSCharacterSet(charactersInString:"`#%^{}\"[]|\\<> ").invertedSet

NSString * resourcePath = @"https://www.xiaocaobank.com";

NSString *encodePath ;

if (!IOS7_OR_LATER) {
encodePath = [resourcePath stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
}else{
encodePath = [resourcePath stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet characterSetWithCharactersInString:@"`#%^{}\"[]|\\<> "].invertedSet];

}