Comments for Jeff Kelley’s Blog

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by Jonice

Jonice — Mon, 28 Nov 2011 11:12:56 +0000

Thanks for the article! its really help me.. on going buid async apps. Thanks again!

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by iphone开发资源汇总 | 漫步人生路

iphone开发资源汇总 | 漫步人生路 — Mon, 24 Oct 2011 02:18:05 +0000

[...] http://blog.slaunchaman.com/2011/02/28/cocoa-touch-tutorial-using-grand-central-dispatch-for-asynchr…/ [...]

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by Jeff Kelley

Jeff Kelley — Thu, 20 Oct 2011 14:20:34 +0000

There definitely is. What you want to do is create your own custom queue:

dispatch_queue_t myQueue = dispatch_queue_create(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0ul);

Then, when you dispatch blocks to this queue, they will execute one-at-a-time and in order. Just make sure when you’re done with the queue you release it:

dispatch_release(myQueue);

iOS 5 has the ability to create custom concurrent queues, but that wouldn’t guarantee that the operations execute in order.

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by utpal

utpal — Thu, 20 Oct 2011 07:18:09 +0000

Hi, Thank for your effort but Is there any way to load asynchronous image in coverflow sequentially. I load images on coverflow but its out of order. I have put its url in array also but still problem occurs to load image in sequentially. Do you have any idea what to do for this then please share with me. Thanks again.

Comment on Dealing with Special Characters in iPhone 4 Graphics Filenames with Subversion by Yatin

Yatin — Wed, 21 Sep 2011 00:05:12 +0000

Thanks for posting. Works well.

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by Kostiantyn Sokolinskyi

Kostiantyn Sokolinskyi — Tue, 20 Sep 2011 10:24:48 +0000

Hi!

Thanks for the idea that large on-disk images can be loaded asynchronously. I hope it can improve my rendering. Before I only considered asynchronous loading for web images.

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells | Jeff Kelley’s Blog | iOS dev (iPhone, iPad) | Scoop.it

Sat, 17 Sep 2011 06:54:35 +0000

[...] Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells | Jeff Kelley&… [...]

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells | Jeff Kelley’s Blog « Programming Iphone API and Tips

Fri, 16 Sep 2011 16:55:21 +0000

[...] Via Scoop.it – iPhone and iPad developmentFrom Jeff Kelley »One of the problems that an iOS developer will often face is the performance of table view cells. Table view cells are loaded on-demand by the UITableView that they’re a part of; the system calls ‑cellForRowAtIndexPath: on the table view’s dataSource property to fetch a new cell in order to display it. Since this method is called (several times) while scrolling a table view, it needs to be very performant. You don’t have very much time to provide the system with a table view cell; take too long, and the application will appear to stutter to your users. This kills the immersion of your application and is an instant sign to users that the application is poorly-written. I guess what I’m saying is that this code needs to be fast. But what if something you need to do to display the table view cell takes a long time—say, loading an image? »Show original [...]

Comment on Cocoa Touch Tutorial: Extract Address Book Address Values on iPhone OS by Jeff Kelley

Jeff Kelley — Mon, 05 Sep 2011 21:33:07 +0000

I have to suggest against doing anything to modify the picker. Introspection of its subviews will work, sure, but Apple is at their leisure to change how that works, reject your application(s) if you mess with it too much, or do something that causes your app to crash when you attempt this. I’m also not aware of any callbacks that you can use to discover when the picker has finished loading; if you absolutely need to do this, you’re going to have to do some introspection to determine this. Since ABPeoplePickerNavigationController is a subclass of UINavigationController, which is itself a subclass of UIViewController, you can probably use the -isViewLoaded method to determine if it’s loaded its view yet. Thanks for the question!

Comment on Cocoa Touch Tutorial: Using Grand Central Dispatch for Asynchronous Table View Cells by jpap

jpap — Sun, 04 Sep 2011 21:58:42 +0000

My apologies: it appears you are in fact using one queue–the global queue–so my query is moot. (My fault for asking before having a full understanding of GCD!)

Thanks again for your post!