Question

我很奇怪的是,如果能够看到存在一个百基百页,我就有一个习惯的搜索,把搜索空间替换为——但我看不出这条道路是否实际存在。

    targetWiki = inputCustomTarget.text;
    targetWiki = [targetWiki stringByReplacingOccurrencesOfString:@" " withString:@"_"];
    targetWiki = [NSString stringWithFormat:@"http://en.m.wikipedia.org/wiki/%@", targetWiki];

如果存在一页,我是否必须把答复同起来?

Answer 1

无需对结果进行核对,以便:https://stackoverflow.com/questions/917932/retrieve-httprequest-status-codes-iphone-sdk>200 回复代码载于<代码>-(避免)联接:NSURLConnection*) 如果不存在,就应当获得404份。

<><>Edit>:

我愿补充说,<>Main上不存在的网页。 Wikipedia页面(不是移动电话)确实退回了正确的404个错误代码。这可能会改变未来,如果改变任何内容,但两者都不会贬低内容,则可能完全可靠。这里是我汇集的样本,以证明这一点。

NSURLRequest *exists = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://en.wikipedia.org/wiki/Qwerty"]];
//Redirects to Blivet
NSURLRequest *redirects = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://en.wikipedia.org/wiki/Poiuyt"]];
NSURLRequest *nonexistant = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://en.wikipedia.org/wiki/Jklfdsa"]];

NSHTTPURLResponse *resp_exists;
NSHTTPURLResponse *resp_redirects;
NSHTTPURLResponse *resp_nonexistant;

[NSURLConnection sendSynchronousRequest:exists returningResponse:&resp_exists error:NULL];
[NSURLConnection sendSynchronousRequest:redirects returningResponse:&resp_redirects error:NULL];
[NSURLConnection sendSynchronousRequest:nonexistant returningResponse:&resp_nonexistant error:NULL];

NSLog(@"
Exists: %d
Redirects: %d
Non Existant: %d", 
      [resp_exists statusCode], 
      [resp_redirects statusCode], 
      [resp_nonexistant statusCode] );

And here is the output

Exists: 200
Redirects: 200
Non Existant: 404

So if a page exists or automatically redirects to a page that does exist you will get a 200 error code, if it does not exist then you will get 404. If you would like to capture the redirect you will need implement -connection:willSendRequest:redirectResponse: and act accordingly.

Note: This example code is synchronous for the sake of being compact. This is not ideal and production implementations should be sending asynchronous request and use the NSURLConectionDelegate methods.

Answer 2

You can t check the response code because it will always return a 200 response code.

I think the best way to see if a page exists is to parse the response and check if you land on the default search results page.

Another option would be to make use of MediaWiki s API.

http://en.wikipedia.org/w/api.php?action=opensearch&search=term

Check if the term that was searched for exists in the returned response.

Answer 3

是的,恐怕你很可能需要把结果同起来,以知道该页是否存在。然而,如果你看一看在此提供的全部英文维基百科式垃圾填埋场档案,则可能有一个替代办法;

http://en.wikipedia.org/wiki/Wikipedia:Database_download#Latest_complete_dump_of_English_Wikipedia

Obviously this raw data is huge, but you could write a parser to find all the valid links and then compress that information into (say) a coreData database which you might find could fit on the iPhone. Then you could run a check without having to test the page.

But to be honest, I d probably parse the page and perhaps cache the answer so I only have to do it once.

EDIT: I m afraid the answer given by Joe is not fully correct. When I use the domain that the original question used (ie en.m.wikipedia.org) then Joe s sample code gives the following output.

Exists: 200
Redirects: 200
Non Existant: 200

If I use en.wikipedia.org then my results concur with Joe, however that was not the question asked. I am based in the UK and that might also have a bearing on the results.

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