objective C process other events within while loop - objective-c

Question

Is there a way to force your application to process other events? I have a loop that is supposed to wait 10 seconds for a json response. The problem seems to be that the loop processes before the didReceiveData event can run.
JsonArray is an NSArray property.
Here is my code in Session.m:
-(BOOL)logIn
{
JsonArray = nil;
if (([Password class] == [NSNull class]) || ([Password length] == 0))
return NO;
if (([Username class] == [NSNull class]) || ([Username length] == 0))
return NO;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:URL_ALL_PROPERTIES]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection start];
if (!connection)
{
return NO;
}
int time = CFAbsoluteTimeGetCurrent();
while (!JsonArray)
{
if (CFAbsoluteTimeGetCurrent() - time == 10)
{
NSLog(#"breaking loop");
break;
}
// process events here
}
if (!JsonArray) return NO;
NSLog(#"JsonArray not nil");
return YES;
}
didReceiveData handler:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
NSLog(#"Data received");
NSError *e = nil;
JsonArray = nil;
JsonArray = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&e];
if (!JsonArray)
{
JsonArray = nil;
Connected = NO;
return;
}
Connected = YES;
}

Answer 1

Embrace the asynchronous nature of what you're trying to do. Remove the return from the login method and add a completion block instead. Store the completion block in a property (copy) and call it from connectionDidFinishLoading:.
typedef void (^MYCompletionHandler)(BOOL success);
#property (nonatomic, copy) void (^MYCompletionHandler)(bool *) completion;
- (void)loginUserWithCompletion:(MYCompletionHandler)completion {
self.completion = completion;
// start your login processing here
}
// when the login response is received
self. completion(##DID_IT_WORK##);
Your current code doesn't work because the main runloop isn't running while your hard loop is running, so the delegate methods are queued waiting to be processed. Don't try to work around it with the run loop, deal with the asynchronous nature properly.

Answer 2

The didReceiveData method will be called when the data has been received. If you need to process the data returned, do it in the delegate method.
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// process your data in here
}
The logIn function has to finish before didReceiveData will be called. You cannot block for a response. That's the nature of NSURLConnection.