Speed up the response retriever from server in iphone

Question

I am using following code to get results from server

        NSString *queryString = @"MyString"

        NSString *response = [NSString stringWithContentsOfURL:[NSURL URLWithString:queryString] encoding:NSUTF8StringEncoding error:&err];

        NSLog(@"%@",response);

        if (err != nil)
        {
            UIAlertView *alert = [[UIAlertView alloc]initWithTitle: @"Error"
                                                           message: @"An error has occurred. Kindly check your internet connection"
                                                          delegate: self
                                                 cancelButtonTitle:@"Ok"
                                                 otherButtonTitles:nil];
            [alert show];
            [indicator stopAnimating];
        }
        else
        {
//BLABLA
}

The problem with this code is ,If server shows lag and it takes lets say 3 seconds to get this response

NSString *response = [NSString stringWithContentsOfURL:[NSURL URLWithString:queryString]

For 3 seconds my iPhone screen is jammed. How can i make it run in background so that it won't slow down or jam the mobile

Regards

Srikar Appalaraju · Accepted Answer · 2013-01-23T08:28:35.730

What you are doing is sending HTTP request from the main thread. that will jam up the UI as you said. You need to spawn a background thread and make a request to your server, when the response comes back then you need to update the UI from the main thread. This is a common pattern in UI coding.

__block__  NSString *response;

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{

    //your server url and request. data comes back in this background thread
    response; = [NSString stringWithContentsOfURL:[NSURL URLWithString:queryString] encoding:NSUTF8StringEncoding error:&err];

    dispatch_async(dispatch_get_main_queue(), ^{
        //update main thread here.
        NSLog(@"%@",response);

        if (err != nil)
        {
            UIAlertView *alert = [[UIAlertView alloc]initWithTitle: @"Error"
                                                           message: @"An error has occurred."
                                                          delegate: self
                                                 cancelButtonTitle:@"Ok"
                                                 otherButtonTitles:nil];
            [alert show];
            [indicator stopAnimating];
        }
    });
});

You can also use performSelectorInBackground:withObject: to spawn a new thread, then the performed selector is responsible for setting up the new thread's autorelease pool, run loop and other configuration details – see "Using NSObject to Spawn a Thread" in Apple's Threading Programming Guide.

You'd probably be better off using Grand Central Dispatch as I posted above. GCD is a newer technology, and is more efficient in terms of memory overhead and lines of code.

can you put an example up of how to use ur code with my code? That would be very nice of you since i am still in my learning process :) — Muhammad Umar, Jan 23 '13 at 08:30
i was wondering if I transfer it in an let's say NSObject class and call it from my UIViewController, however when i do this, it doesn't work. I want to do this because i have to use it a lot of places , large code, so instead i just pass url and return response? — Muhammad Umar, Feb 05 '13 at 08:26

score -1 · Answer 2 · answered Jan 23 '13 at 08:23

-1

You could use ASIHTTPRequest which is my favorite for getting and sending information.

answered Jan 23 '13 at 08:23

Manuel

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Speed up the response retriever from server in iphone

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