NSString 中包含中文字符时转换为NSURL

- (NSString *)stringByAddingPercentEscapesUsingEncoding:(NSStringEncoding)encoding

- (NSString *)stringByReplacingPercentEscapesUsingEncoding:(NSStringEncoding)encoding

NSString* messageBody = @"中文";
//编码
messageBody =[messageBody stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//解码
messageBody =[messageBody stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];