转载自：http://my.oschina.net/wangdk/blog/165554
NSURL *url = [NSURL URLWithString:@"http://www.baidu.com/searchid=1"];
NSLog(@"scheme:%@", [url scheme]); //协议 http
NSLog(@"host:%@", [url host]); //域名 www.baidu.com
NSLog(@"absoluteString:%@", [url absoluteString]); //完整的url字符串 http://www.baidu.com:8080/search?id=1
NSLog(@"relativePath: %@", [url relativePath]); //相对路径 search
NSLog(@"port :%@", [url port]); // 端口 8080
NSLog(@"path: %@", [url path]); // 路径 search
NSLog(@"pathComponents:%@", [url pathComponents]); // search
NSLog(@"Query:%@", [url query]); //参数 id=1
