Error Domain=NSURLErrorDomain Code=-1002 "unsupported URL"

“Error Domain=NSURLErrorDomain Code=-1002 "unsupported URL"”

bug产生的原因：
URL 不能包含 ASCII 字符集。

解决的办法：
把url的字符串进行如下处理。

urlString = [urlString  stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

/***
stringByAddingPercentEncodingWithAllowedCharacters 对字符串进行编码
  URLFragmentAllowedCharacterSet                                "#%<>[\]^`{|}  
  URLHostAllowedCharacterSet                                    "#%/<>?@\^`{|}  
  URLPasswordAllowedCharacterSet                                "#%/:<>?@[\]^`{|}  
  URLPathAllowedCharacterSet                                    "#%;<>?[\]^`{|}  
  URLQueryAllowedCharacterSet                                   "#%<>[\]^`{|}  
  URLUserAllowedCharacterSet                                    "#%/:<>?@[\]^`
***/