第一種： 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]; 

NSURLResponse *respone;
NSError *error;
NSData *myReturn =[NSURLConnection sendSynchronousRequest:request returningResponse:&respone
error:error];
NSLog(@"%@", [[NSString alloc] initWithData:myReturn encoding:NSUTF8StringEncoding]);
}

第二種，采用事件代理方式

-(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]; 

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 
} 

}

 

// 收到響應時, 會觸發
- (void)connection:(NSURLConnection *)connection  didReceiveResponse:(NSURLResponse *)response  {
// 注意這裡將NSURLResponse對象轉換成NSHTTPURLResponse對象才能去
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)response;
if ([response respondsToSelector:@selector(allHeaderFields)]) {
NSDictionary *dictionary = [httpResponse allHeaderFields];
NSLog([dictionary description]);
NSLog(@"%d",[response statusCode]);

}
}

// Forward errors to the delegate.
//鏈接錯誤  
- (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.
//接收數據 每收到一次數據, 會調用一次
- (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];

}
//接收結束
- (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.
}

摘自 進階碼農的專欄