Make lazy loading faster and responsive in iOS App - objective-c

Question

In my iOS app I've a class that performs a web request to get an array of informations located in mySQL DB. In this class I've a method that do this taking as input a mySQL query:
- (NSMutableArray *) myreq:(NSString *)query{
// Create NSData object
NSData *dataQuery = [query
dataUsingEncoding:NSUTF8StringEncoding];
// Get NSString from NSData object in Base64
NSString *base64EncodedQuery = [dataQuery base64EncodedStringWithOptions:0];
// Print the Base64 encoded string
NSLog(#"Encoded: %#", base64EncodedQuery);
NSMutableString *strURL = [NSMutableString stringWithFormat:#"http://…=%#“,base64EncodedQuery];
[strURL setString:[strURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSData *dataURL = [NSData dataWithContentsOfURL:[NSURL URLWithString:strURL]];
NSError* error;
NSDictionary* json = [NSJSONSerialization
JSONObjectWithData:dataURL
options:kNilOptions
error:&error];
NSMutableArray *results = [[NSMutableArray alloc] init];
int numRow = 0;
for (NSArray *arrow in json) {
[results addObjectsFromArray:arrow];
numRow++;
}
return results;
}
This method send a query to a php script that perform immediately this query to MySQL DB and get a json with results. I translate the json in this method and finally return an array with results.
I call myreq in a method
- (void)downloadScope{
_arrID = [[NSMutableArray alloc] init];
_arrIDUsers = [[NSMutableArray alloc] init];
_arrUsernames = [[NSMutableArray alloc] init];
_arrPictures = [[NSMutableArray alloc] init];
[myQueue addOperation:[NSBlockOperation blockOperationWithBlock: ^{
query = #"SELECT ID FROM mytable”;
[_arrID addObjectsFromArray:[self myreq:query]];
for (int i = 0; i < [_arrID count]; i++) {
NSArray *tempArray = [[NSArray alloc] initWithArray:[self myreq:[NSString stringWithFormat:#"SELECT IDUsr,usrn, pictureaddress FROM mytable WHERE ID = %#",_arrID[i]]]];
[_arrIDUsers insertObject:tempArray[0] atIndex:i];
[_arrUsernames insertObject:tempArray[2] atIndex:i];
[_arrPictures insertObject:tempArray[2] atIndex:i];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
[self.tableView reloadData];
}];
}
}]];
[myQueue setSuspended:NO];
}
In tableView I create cells in this way (using SDWebImage):
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//Identificatore di cella
NSString *identifier = #“cellmy”;
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
cell.backgroundColor = nil;
if ( cell == nil ) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
}
NSString *username = [self.arrUsernames objectAtIndex:indexPath.row];
UILabel *cellLabelUsername = (UILabel *)[cell viewWithTag:2];
cellLabelUsername.text = [username uppercaseString];
UIImageView *cellImageProfileSnap = (UIImageView *)[cell viewWithTag:5];
[cellImageProfileSnap sd_setImageWithURL:[NSURL URLWithString:[_arrPictures objectAtIndex:indexPath.row]] placeholderImage:[UIImage imageNamed:#“…”]];
}
In viewDidLoad I initialize my NSOperationQueue (defined in my interface):
myQueue = [[NSOperationQueue alloc] init];
[myQueue setMaxConcurrentOperationCount:100];
[myQueue setName:#"com.sada"];
My goal is to make everything faster because the loading in tableView is slow and I think that is not dependent on SDWebImage. Please help me