code hangs

[salmanlodhi]

I created a new project for your code. Its working fine on simulator.

As soon as i test on IPhone4S .... Program hangs during execution of below code

static LARSAdController *_sharedManager;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedManager = [[super allocWithZone:NULL] init];
});

So somehow when its creating the manger in the block..... its delayed or kind of stuck ..... Any idea what is missing ???

[salmanlodhi]

When I paused the execution in Xcode.... program is stuck on this piece of Apple provided code

---

void
dispatch_once(dispatch_once_t *predicate, dispatch_block_t block);

DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
void
_dispatch_once(dispatch_once_t _predicate, dispatch_block_t block)
{
if (DISPATCH_EXPECT(_predicate, ~0l) != ~0l) {
dispatch_once(predicate, block);
}
}

---

..... exactly on dispatch_once(predicate, block); function

[larsacus]

That's a pretty basic couple of lines of code. If it's hanging anywhere it is in the allocWithZone: method of the superclass, which is simply an NSObject. So there's really not much that can fail here, unless you have your project setup incorrectly with regards to ARC/Non-ARC.

[salmanlodhi]

ARC is disabled....

only missing thing was the compiler flag for LARSadcontroller.m .. I even added that ..... but still same issue

This code works fine on simulator but only hangs on iPhone ....

[salmanlodhi]

Now I created a new project and its getting stuck on same line with Simulator and Device :(

[larsacus]

It's your environment. There is nothing wrong with the code you're talking about. I can say that with confidence because the section in question that it's "hanging" on is all Foundation code and not my own. Try cleaning your build, deleting the app from both the simulator and the device, close Xcode, and restart your computer.

Also, try running the sample project included with the source code.

[salmanlodhi]

Okie..its all happening due to threading...if i remove this dispatch_once thing then it works fine...only thing is that it keeps loading again and again

[larsacus]

That's because dispatch_once is the singleton initializer that guarantees that the system will only call it once and it will be a no-op on subsequent calls

[salmanlodhi]

How about i use some global variable value to determine ... if it needs to be instantiated ?

[larsacus]

That's exactly what static dispatch_once_t onceToken; is doing. After the token is set on the first execution (thus why you are passing it in by reference to dispatch_once with &onceToken), dispatch_once does not fire what is in it's block. Are you calling these methods from a thread other than the main thread?

This code is running fine on tens of thousands of devices in production.

[salmanlodhi]

I know your code is fine..... it works in other project made by me

I am calling this code in view will appear of the first View Controller that the app loads .... i created a new project .... with only one view controller then it worked fine.... now as soon as i included my other view controllers (already written previously)........ same behavior is returned....

[larsacus]

Not sure what to say without seeing the project.

[salmanlodhi]

could this be possible reason

"dispatch_once will deadlock if the something in the -init method calls the +singleton method. "

source : http://cocoasamurai.blogspot.com/2011/04/singletons-your-doing-them-wrong.html

[salmanlodhi]

wait a minute .... i just checked that i load data from files in my app delegate.... in function didFinishLaunchingWithOptions

if i remove data load function then ads are displayed......

[salmanlodhi]

I created a global variable which i initialize in didFinishLaunchingWithOptions function in delegate......

In rest of code in just refer to this variable which is of type LARSAdController.

Problem Solved :)