iphone网络post连接的两种处理方式(同步和异步)

iphone网络post连接的两种处理方式(同步和异步)  
第一种： 直接返回方式。
-(void)UpadaPost:(NSString *)strcontext URL:(NSString *)urlstr{
NSLog(urlstr);
NSLog(strcontext);
assert(strcontext != NULL);
assert(urlstr != NULL);
NSData *postData = [strcontext dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];  
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];  
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];  
[request setURL:[NSURL URLWithString:urlstr]];  
[request setHTTPMethod:@"POST"];  
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];  
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];  
[request setHTTPBody:postData];  

NSURLResp*****e *respone;
NSError *error;
NSData *myReturn =[NSURLConnection sendSynchronousRequest:request returningResp*****e:&respone
error:error];
NSLog(@"%@", [[NSString alloc] initWithData:myReturn encoding:NSUTF8StringEncoding]);
}
第二种，采用事件代理方式(重要）
使用TouchXML时，常用到下面的代码

-(void)UpadaPost:(NSString *)strcontext URL:(NSString *)urlstr{
NSLog(urlstr);
NSLog(strcontext);
assert(strcontext != NULL);
assert(urlstr != NULL);
NSData *postData = [strcontext dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];  
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];  
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];  
[request setURL:[NSURL URLWithString:urlstr]];  
[request setHTTPMethod:@"POST"];  
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];  
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];  
[request setHTTPBody:postData];  

NSURLConnection *conn=[[NSURLConnection alloc] initWithRequest:request delegate:self];  
if (conn)    
{  
NSLog(@"Connection success");
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
[conn retain];

}    
else    
{  
// inform the user that the download could not be made  
}  
}

// 收到响应时, 会触发
- (void)connection:(NSURLConnection *)connection  didReceiveResp*****e:(NSURLResp*****e *)resp*****e  {
// 注意这里将NSURLResp*****e对象转换成NSHTTPURLResp*****e对象才能去
NSHTTPURLResp*****e *httpResp*****e = (NSHTTPURLResp*****e*)resp*****e;
if ([resp*****e respondsToSelector:@selector(allHeaderFields)]) {
NSDictionary *dictionary = [httpResp*****e allHeaderFields];
NSLog([dictionary description]);
NSLog(@"%d",[resp*****e statusCode]);

}
}

// Forward errors to the delegate.
//链接错误   
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
//[self performSelectorOnMainThread:@selector(httpConnectEnd) withObject:nil waitUntilDone:NO];
NSLog(@"%@",[error localizedDescription]);

}
// Called when a chunk of data has been downloaded.
//接收数据 每收到一次数据, 会调用一次
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
// Process the downloaded chunk of data.

NSLog(@"%d", [data length]);
//NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

//[self performSelectorOnMainThread:@selector(updateProgress) withObject:nil waitUntilDone:NO];


}
//接收结束
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

NSLog(@"%@",connection);
//NSLog(@"%lld", received_);

//[self performSelectorOnMainThread:@selector(httpConnectEnd) withObject:nil waitUntilDone:NO];
// Set the condition which ends the run loop.
}