objective-c - 正确处理 NSURLConnection 错误

Question

我设置了一个简单的表单界面，将用户名和密码信息发送到服务器:(工作)

    NSString *postData = [NSString stringWithFormat:@"user=%@&pass=%@",[self urlEncodeValue:sysUsername],[self urlEncodeValue:password]];
NSLog(@"Post data -> %@", postData);
///
NSData* postVariables = [postData dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSMutableURLRequest* request = [[[NSMutableURLRequest alloc] init] autorelease];
NSString* postLength = [NSString stringWithFormat:@"%d", [postVariables length]];
NSURL* postUrl = [NSURL URLWithString:@"http://localhost/~csmith/cocoa/test.php"];
[request setURL:postUrl];
[request setHTTPMethod:@"POST"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody: postVariables];

NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:NULL error:NULL];
NSLog(@"Post data SENT & returned -> %@", returnData);

如何处理连接错误，例如没有互联网连接、防火墙等。另外，此方法是否使用系统范围的代理设置？我的许多用户都使用代理。

非常感谢!

Answer 1

首先，您不应使用同步请求，而应使用异步请求，并使用 indeterminate progress indicators 指示事件.

使用异步请求时，必须设置委托(delegate)实现delegate methods ，特别是:

• -connectionDidFinishLoading:
• -connection:didFailWithError:

来自文档:

Unless a NSURLConnection receives a cancel message, the delegate will receive one and only one of connectionDidFinishLoading:, or connection:didFailWithError: message, but never both. In addition, once either of messages are sent, the delegate will receive no further messages for the given NSURLConnection.

至于最后一个问题:

Also, does this method use the system-wide proxy settings?

是的，NSURLConnection会自动使用它们。