NSRunLoop控制下载

I am currently working on perfecting my new AppReviews application. It sure coming along nicely but I ran into some trouble.
Because I am pulling a lot of data from the web, I wanted to update a progress bar when data arrives and show the user some progress. Of course you can normally do this by putting your web activity in a separate thread and making sure that thread notifies your main thread when changes occur.
Well, in Cocoa this isn’t that simple. For my web activities I created a new class and when I want to pull data from the web I do that by putting it in it’s own thread.

  1. NSString* url = @"http://your.url/here";

  2. NSURL* nsurl = [NSURL URLWithString:url];

  3. NSMutableURLRequest* urlReq = [[NSMutableURLRequest alloc] initWithURL:nsurl];

  4. NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:urlReq delegate:self];


My class contains all the necessary delegate methods like :

  1. - (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data;

  2. - (void) connectionDidFinishLoading:(NSURLConnection *)connection;

But once the NSURLConnection is launched in a seperate thread, the delegate methods do not get triggered anymore. This probably because the thread is finished before your class actually executed all it’s code.
After you initialized the NSURLConnection object, you actually need to put the class in an infinite loop to make sure the class is still alive when the delegate methods are hit.
For example:
NSString* url = @"http://your.url/here";
NSURL* nsurl = [NSURL URLWithString:url];
NSMutableURLRequest* urlReq = [[NSMutableURLRequest alloc] initWithURL:nsurl];
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:urlReq delegate:self];
while(!finished) {
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}
- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
finished = TRUE;
}
finished’ is a bool variable, which declare in your .h file.
Hope this helps some people out, because this bugged for a while…..