NSLock *countingLock = [[NSLock alloc] init];
__block NSInteger numberOfRequests = 0;
for(NSURL* url in URLArray){
@synchronized(countingLock){ numberOfRequests++; }
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
UIImage* serverImage = [UIImage imageWithData:data];
@synchronized(countingLock){
if( --numberOfRequests == 0 )
NSLog( @"OWARI DENGANA" );
}
}];
}

直した