[TC-1101] Added Ti.App.Properties 'change' event for iOS

[farfromrefug]

I added a "change" event to Ti.App.Properties to listen for changes of Properties

[negupta]

Signed CLA is in place.

[negupta]

@farfromrefug - We need a JIRA ticket and a test case to process this PR.

[farfromrefug]

Will do thanks

[farfromrefug]

JIRA ticket + test case
https://jira.appcelerator.org/browse/TC-1101

[WhichKatieDid]

Forwarded questions internally about if there'd be any issue with Android or Mobile Web implementing this, too. CR edge case: It's highly unlikely, but could you add:

TiThreadPerformOnMainThread(^{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}, YES);

in the beginning of TiAppPropertiesProxy's dealloc? There is a possibility that the proxy is removed before a listener is.

Similarly, you will need to have

TiThreadPerformOnMainThread(^{<YOUR CODE>}, YES);

around any access to nsnotificationcenter, since it's not threadsafe and the _listenerAdded/removed happens in a background thread.

[farfromrefug]

yes you are right!

[farfromrefug]

About android implementation i didnt see any way to change properties outside application so i didnt see the need for such implementation

[WhichKatieDid]

CR approved, generated TIMOB-10260 and TIMOB-10262 for parity, in case you want to add to the pull request on other OSes.

[WhichKatieDid]

FR passed. Merging pull.

[farfromrefug]

I will look at it. By the way shouldnt we add documentation for this ? (that would be my first so a good thing ;))