1.首先明确下顺序：

Eg:"POST"情况:string->NSData,NSMutableURLrequest,NSURLConnection,NSURLResponse

staticNSString*body

=@"aaaaaa";//要POST的输入string

staticNSString*URLString

=@"http://earthquake.usgs.gov/eqcenter/catalogs/7day-M2.5.xml";

NSData *dataBody

= [NSData dataWithBytes:

[stringBody UTF8String] length:

[body length]];//将string封装成NSData类型的数据

NSMutableURLRequest*request

= [[NSMutableURLRequestalloc]initWithURL:[NSURLURLWithString: URLString]];

//发送请求，正式发送

[request setHTTPMethod:@"POST"];

[request setHTTPBody:dataBody];

NSURLResponse*response;

NSError *error;

[NSURLConnectionsendSynchronousRequest:requestreturningResponse:&responseerror:&error];//发送同步连接＋反馈请求

//在NSCocoaErrorsDomain领域中，除非你知道具体的CFNetWorkError类型，非则用[Error

code]便利构造

if(error){

NSError *locatedError

= [NSError errorWithDomain:NSCocoaErrorDomain code:[error code] userInfo:[NSDictionarydictionary]];

//本地化描述具体的错误，用NSInteger返回ui,告知用户

NSString *errorMessage

= [locatedError localizedDescription];

//以下是弹出警告，为了UI的友好性要求

UIAlertView*alertV

iew = [[UIAlertViewalloc]initWithTitle:NSLocalizedString(@"Error

Title",@"")message:errorMessagedelegate:nilcancelButtonTitle:@"OK"otherButtonTitles:nil];

[alertView show];

[alertView release];

}

2.Eg：默认"GET"情况:NSMutableURLrequest,NSURLConnection,NSURLRespons,String->NSData

>>>同上

[URLRequest setHTTPMethod:@"GET"];//默认为GET,否则是POST，也可不加

//连接失败，则抛出异常，如有2中delegate监听，亦可不加

NSAssert(self.earthquakeFeedConnection!=nil,@"Failure

to create URL connection.");

//连接等待标志，必加的

[UIApplication

sharedApplication].networkActivityIndicatorVisible

= YES;

2.哦了，以上的连接是最经典的代码，可以进行NSURLConnection

delegate监听了～

1>

- (void)connection:(NSURLConnection *)connection

didReceiveResponse:(NSURLResponse *)response

{

//这里写些对response的处理，一般是些error处理，可以不在这里处理直接跳转到3>

}

2>

- (void)connection:(NSURLConnection *)connection

didReceiveData:(NSData *)data

{

//这里写些对data数据的处理，一般是初始化数据后，将data写入

}

3>

- (void)connection:(NSURLConnection *)connection

didFailWithError:(NSError *)error

{

[UIApplication sharedApplication].networkActivityIndicatorVisible

= NO;

//在NSCocoaErrorsDomain领域中，除非你知道具体的CFNetWorkError类型，非则用[Error

code]便利构造

NSError*locatedError

= [NSErrorerrorWithDomain:NSCocoaErrorDomaincode:[errorcode]userInfo:[NSDictionarydictionary]];

//本地化描述具体的错误，用NSInteger返回ui,告知用户

NSString *errorMessage

= [locatedError localizedDescription];

//以下是弹出警告，为了UI的友好性要求

UIAlertView*alertView

= [[UIAlertViewalloc]initWithTitle:NSLocalizedString(@"Error

Title",@"")message:errorMessagedelegate:nilcancelButtonTitle:@"OK"otherButtonTitles:nil];

[alertView show];

[alertView release];

}

OVER,

以上是从xml获取信息移植到自定义app中的错误处理过程，～～