I am developing one small app in which i have multiple NSURLConnection.I have created that NSURL Connection but i don't know how to handle it.My code is like below.
-(void) loadTrafficAndEvent {
int a=10;
//Get the map view bounds for fetch the travel time markers from web service
MKCoordinateRegion region = mapView.region;
float print = region.center.latitude;
// NSLog(@"region.center=%g",print);
CGPoint firstcorner = CGPointMake(self.mapView.bounds.origin.x , mapView.bounds.origin.y);
CGPoint secondcorner = CGPointMake((self.mapView.bounds.origin.x+mapView.bounds.size.width) , mapView.bounds.origin.y);
CGPoint thirdcorner = CGPointMake(self.mapView.bounds.origin.x , (mapView.bounds.origin.y+ mapView.bounds.size.height));
CGPoint fourthcorner = CGPointMake((self.mapView.bounds.origin.x+mapView.bounds.size.width), (mapView.bounds.origin.y + mapView.bounds.size.height));;
//Then transform those point into lat,lng values
CLLocationCoordinate2D mapfirstcorner,mapsecondcorner,mapthirdcorner,mapfourthcorner,requestsender;
mapfirstcorner = [mapView convertPoint:firstcorner toCoordinateFromView:mapView];
mapsecondcorner = [mapView convertPoint:secondcorner toCoordinateFromView:mapView];
mapthirdcorner = [mapView convertPoint:thirdcorner toCoordinateFromView:mapView];
mapfourthcorner = [mapView convertPoint:fourthcorner toCoordinateFromView:mapView];
NSDateFormatter *dateFormatter;
dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MM-dd-yyyy"];
NSString *date = [dateFormatter stringFromDate:[NSDate date]];
[dateFormatter release];
NSString *checksumString = [NSString stringWithFormat:@"TrafficAndEvents%@ForTravelStar", date];
NSString *md5Checksum = [self getMD5CheckSum:checksumString];
NSString *url = [NSString stringWithFormat:@"http://www.travelstar.nl/travelstarwebservice/ProviderServices.asmx/GetTrafficStatusAndEvent?northWestLatitude=%f&northWestLongitude=%f&southEastLatitude=%f&southEastLongitude=%f&zoomLevel=%d&date=%@&checksum=%@", mapfirstcorner.latitude,mapfirstcorner.longitude, self.mapView.region.center.latitude, self.mapView.region.center.longitude, a,date,md5Checksum];
NSString *url1 = [NSString stringWithFormat:@"http://www.travelstar.nl/travelstarwebservice/ProviderServices.asmx/GetTrafficStatusAndEvent?northWestLatitude=%f&northWestLongitude=%f&southEastLatitude=%f&southEastLongitude=%f&zoomLevel=%d&date=%@&checksum=%@", mapsecondcorner.latitude,mapsecondcorner.longitude, self.mapView.region.center.latitude, self.mapView.region.center.longitude, a,date,md5Checksum];
NSString *url2 = [NSString stringWithFormat:@"http://www.travelstar.nl/travelstarwebservice/ProviderServices.asmx/GetTrafficStatusAndEvent?northWestLatitude=%f&northWestLongitude=%f&southEastLatitude=%f&southEastLongitude=%f&zoomLevel=%d&date=%@&checksum=%@", mapthirdcorner.latitude,mapthirdcorner.longitude, self.mapView.region.center.latitude, self.mapView.region.center.longitude, a,date,md5Checksum];
NSString *url3 = [NSString stringWithFormat:@"http://www.travelstar.nl/travelstarwebservice/ProviderServices.asmx/GetTrafficStatusAndEvent?northWestLatitude=%f&northWestLongitude=%f&southEastLatitude=%f&southEastLongitude=%f&zoomLevel=%d&date=%@&checksum=%@", mapfourthcorner.latitude,mapfourthcorner.longitude, self.mapView.region.center.latitude, self.mapView.region.center.longitude, a,date,md5Checksum];
//Release the request if it is already created.
if(request1 ) {
[request release];
request = nil;
}
else if(request1 ) {
[request1 release];
request1 = nil;
}
else if(request2 ) {
[request2 release];
request2 = nil;
}
else if(request3 ) {
[request3 release];
request3 = nil;
}
//Release the connection if it is already created.
if(conn) {
[conn cancel];
[conn release];
conn = nil;
}
else if(conn1) {
[conn1 cancel];
[conn1 release];
conn1 = nil;
}
else if(conn2) {
[conn2 cancel];
[conn2 release];
conn2 = nil;
}
else if(conn3) {
[conn3 cancel];
[conn3 release];
conn3 = nil;
}
//If zoom level is grater then 6 then it will request for fetch the travel time markers from the web servce.
if(a > 6) {
ZOOM_LEVEL = a;
//Create the request for fetch the data from web service.
request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
request1 = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:url1]];
request2 = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:url2]];
request3 = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:url3]];
//NSLog(@"%@",url);
//NSLog(@"Request sent");
//entryDate = [NSDate date];
//[entryDate retain];
//Create the connection with the web service for fetch the data
// DownloadDelegate *dd = [[DownloadDelegate alloc] init];
conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
conn1 = [[NSURLConnection alloc] initWithRequest:request1 delegate:self];
conn2 = [[NSURLConnection alloc] initWithRequest:request2 delegate:self];
conn3 = [[NSURLConnection alloc] initWithRequest:request3 delegate:self];
}
}
Declare conn,conn1,conn2,conn3 in .h file. Then do the following. in loadTrafficAndEvent:
conn1 = [[NSURLConnection alloc] initWithRequest:request1 delegate:self];
in connectionDidFinishDownloading: method,
- (void)connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL{
if(connection==conn){
conn1 = [[NSURLConnection alloc] initWithRequest:request1 delegate:self];
}
else if(connection==conn1){
conn2 = [[NSURLConnection alloc] initWithRequest:request2 delegate:self];
}
else if(connection==conn2){
conn3 = [[NSURLConnection alloc] initWithRequest:request3 delegate:self];
}
}
Do the operations inside each if else condition, and no need to allocate and initialize all NSURLConnection in loadTrafficAndEvent: The download will occur one after other.
you might want to take a look at AFNetworking for an easier and tidier way of doing network requests.
Implement NSURLConnection delegate methods and rest will be handle by itself
来源：https://stackoverflow.com/questions/9062393/how-can-we-handle-multiple-nsurlconnection-in-iphone-xcode