Comments on: iPhone Coding â€“ Turbo Charging Your Apps With NSOperation

By: Mr. Kela

Mr. Kela — Tue, 07 Feb 2012 20:09:00 +0000

The biggest confusion surrounding NSOperation comes from the distinction between concurrent and non-concurrent operations. If you’re using NSOperationQueue
to run your operations, they’ll always run in parallel as long as the
operations’ prerequisites are met and you have enough processors.

In the original NSOperation terminology, a concurrent operation had an asynchronous API. It had a -start
method that was expected to return quickly. It would spawn a thread,
make an asynchronous API call, or perform some equivalent in this
method. The operation queue then used key-value observing on the isExecuting and isFinished keys to get a notification when the operation had finished.

The point of this distinction was to reduce the overhead of thread creation. Non-concurrent operations just have a -main
method. The original operation queue would execute this method in a
separate thread for each operation that was running, while concurrent
operations could be multiplexed onto a single thread.

By: Mr. Kela

Mr. Kela — Mon, 06 Feb 2012 21:30:00 +0000

tolga: Oh really? Do you really check/analyze the solution before posting any comment?
Run the code enabling breakpoints on the methods that loads the data from server, and see in the “debug navigator” on which thread data is being loaded.

NSOperationQueue is smart enough to only create about as many threads as there are cores, queuing the remaining operations. NSOperationQueue is free to switch to a smarter implementation (like Grand Central Dispatch) now or in the future. It has some other nice constructs built-in, such as a sophisticated way of honoring operation priorities and dependencies.

By: Mr. Kela

Mr. Kela — Mon, 06 Feb 2012 21:11:00 +0000

baabroo daabroo, great tutorialaabroo!

By: Raaf Vk

Raaf Vk — Thu, 02 Feb 2012 12:37:00 +0000

awesommm, great jo

By: tolga

tolga — Thu, 19 Jan 2012 20:20:00 +0000

Did you actually compile and test your code before posting it here? Because, the “correct” solution is almost identical to the “wrong” one. NSInvocationOperation implements a non-concurrent operation (see reference: http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/NSInvocationOperation_Class/Reference/Reference.html). So, all operations will execute on the same thread, which, in your case is the main thread.

By: raees

raees — Sat, 14 Jan 2012 19:53:00 +0000

supeeeerrrrrrrrrrrrrrrrr

By: Abdullah Umer

Abdullah Umer — Mon, 09 Jan 2012 12:55:00 +0000

The [super dealloc] should be called in the end of -(void)dealloc{}.

By: Sabau Radu

Sabau Radu — Thu, 15 Dec 2011 09:26:00 +0000

very good tutorial , I’d love to see a more complex NSOperation tutorial . Thanks for the example

By: Sharlon Balbalosa

Sharlon Balbalosa — Sun, 04 Dec 2011 00:12:00 +0000

I am researching about NSOperation because somebody in stackoverflow that I should avoidÂ [NSThreadÂ detachNewThreadSelector:Â toTarget:Â withObject:]Â What is the advantage of using this?

By: Steve Wu

Steve Wu — Tue, 01 Nov 2011 13:10:00 +0000

Simple and Great Tutorial