如何從 iPhone 中的 url 獲取數據

Question

我是 iPhone 的新開發者。我必須從這個 URL 中獲取名稱

任意 API URL

在表格視圖中..我該怎么做，請幫助我..我通過建立連接來嘗試這個，但它顯示 HTTP 超時錯誤。這是什么原因，還有其他方法可以獲取數據。 .

這是我的連接代碼...

static NSString *feedURLString =
> @"http://www.XXXXX.com/XXXXXX/api/XXXXX.php?method=All";

>     NSURLRequest *studentURLRequest =[NSURLRequest requestWithURL:[NSURL URLWithString:feedURLString]];

>self.studentFeedConnection =[[[NSURLConnection alloc] initWithRequest:studentURLRequest
> delegate:self] autorelease]; 
NSAssert(self.studentFeedConnection != nil, @"Failure to create URL connection."); 
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

> [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(addstudent:)    name:kAddstudentNotifm object:nil];

>[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(studentError:) name:kstudentErrorNotif object:nil];

> - (void)connection:(NSURLConnection *)connection
> didReceiveResponse:(NSURLResponse *)response { NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;

> if ((([httpResponse statusCode]/100) == 2) && [[response MIMEType]
> isEqual:@"application/atom+xml"]) {
>  self.studentData = [NSMutableData data];
>  } 
else {
>         NSDictionary *userInfo = [NSDictionary dictionaryWithObject:NSLocalizedString(@"HTTP Error", @"Error message
> displayed when receving a connection error.")
>                                                             
> forKey:NSLocalizedDescriptionKey];

NSError *error = [NSError errorWithDomain:@"HTTP" code:[httpResponse statusCode]userInfo:userInfo];

> [self handleError:error];

>} 
}
> 
> - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
> [studentData appendData:data]; 
}
> 
> - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
>     [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

> if ([error code] == kCFURLErrorNotConnectedToInternet) {
>         // if we can identify the error, we can present a more precise message to the user.
> NSDictionary *userInfo = [NSDictionary dictionaryWithObject: NSLocalizedString(@"No Connection Error", @"Error message displayed when not connected to the Internet.")forKey:NSLocalizedDescriptionKey];

>NSError *noConnectionError = [NSError errorWithDomain:NSCocoaErrorDomain code:kCFURLErrorNotConnectedToInternet userInfo:userInfo];
> [self handleError:noConnectionError];
>} 
else {
>// otherwise handle the error generically
>[self handleError:error];
>}
> self.studentFeedConnection = nil;
}

Answer 1

嘗試使用 NSXMLParser

NSString *site = [NSString stringWithString:
    @"http://www.XXXXX.com/XXX/api/XXXX.php?method=All"];
NSURL *url = [NSURL URLWithString:site];
NSXMLParser *myparser =  [NSXMLParser initWithContentsOfURL:url];
myparser.delegate = self;
[myparser parse];

確保執行

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI  qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict;

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string;

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError;

- (void) parserDidEndDocument:(NSXMLParser *)parser;

將數據解析為 NSArray 或 NSDictionary 后，您可以將其用作 UITableView 中的數據源

Answer 2

如果您收到 HTTP 錯誤，那么您的連接方式很可能有問題。 您的連接是否需要身份驗證？ 如果是這樣，您將需要實施：

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
    NSURLCredential *myCreds = [[NSURLCredential alloc] initWithUser:@"**USERNAME**" password:@"**PASSWORD**" persistence:NO];

    [challenge.sender useCredential:myCreds forAuthenticationChallenge:challenge];
    [myCreds release];
}

至於實際檢索數據，如您需要使用 NSXML Parser，您可以在此處查看詳細信息： http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class /參考/參考.html 。 您必須實現的只有 3 個方法，其余的只是獎勵。 這三個是

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI  qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict;

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string;

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName;

理想情況下，您知道您正在解析的 XML 的結構，因為您需要識別上述函數中的元素/屬性名稱。 然后，您可以將數據存儲在數組中，或者任何最適合的方式。

您還可以選擇使用第 3 方解析器，這里有各種可用解析器的很好的解釋/比較： http://www.raywenderlich.com/553/how-to-chose-the-best-xml -parser-for-your-iphone-project

希望這可以幫助！