update to 2.16.0

[msach22]

Pull request checklist

• All tests pass. Demo project builds and runs.
• I have resolved any merge conflicts. Confirmation: ____

This fixes issue #___.

What's in this pull request?

Updates library to 2.15.0

...

[msach22]

@jtiet shouldn't we use 2.16.1 so we don't have the logging issue that we had with 2.16.0?

[jtiet]

Thanks for the reminder @msach22, I changed it to use 2.16.1.

[robjperez]

I think it is a good practice to run pod deintegrate before checking the project file.

This way we remove pod reference in the project file

[jtiet]

Thank you for the suggestion @robjperez! Fixed, please check again

[robjperez]

when you use self in a block it is good practice (to avoid reference loops) to capture a weak reference to it.

See: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/WorkingwithBlocks/WorkingwithBlocks.html#//apple_ref/doc/uid/TP40011210-CH8-SW16

[jtiet]

thanks @robjperez. Fixed, please check again

[robjperez]

Actually you don't need a strong reference here.

weak reference means that if when you execute this block, self is already disposed, it won't crash when you try to access timer property.

IMHO, it should be something like this:

__weak __typeof__(self) *weakSelf = self;
dispatch_sync(_queue, ^{
      dispatch_source_cancel([weakSelf timer]);
}

[jtiet]

Thanks, fixed it.

[jtiet]

Could you please share why a weak reference is needed in this case? I understand that weak should be used within blocks because if self references the block and the block references self, this creates a reference loop. In this case, it looks like the block would retain self, but since the block is not assigned to a variable, I don't think that self retains the block. So if one or the other is released, everything gets deallocated properly.

So that would mean the following should work:

    _capturing = NO;
    dispatch_sync(_queue, ^{
        if (self->_timer) {
            dispatch_source_cancel(self->_timer);
        }
    });

I'd also like to add that since _timer is a property, [weakSelf _timer] would throw the following error (in travis tests):
bad receiver type 'OTScreenCapture *const __weak *'

[robjperez]

the weak reference is useful in two ways. one is for the capture part, and to prevent cycles that could make self never be released as you have explained.

The other one is to prevent crashes. As blocks are executed in a different thread, when the block is executed it could happen that self has been released so self->_timer will have undefined behavior. That's where weak helps, if you have a weak reference, if self is released, when you do [weakSelf timer] it won't crash since weakSelf is set to nil automatically. (you should not use direct dereference too).

In this particular case probably it doesn't matter since it is a dispatch_sync block and self will not be released when the block is executed. But it is usually a good practice to do the weak thing in any case. That way, if someone in the future, decides to change dispatch_sync with dispatch_async the block is safe.