replace NSOperation mainQueue with dispatch async
replace NSOperation mainQueue with dispatch async

applideveloper/ObjectiveCDM,applideveloper/ObjectiveCDM,applideveloper/ObjectiveCDM,jameshuynh/ObjectiveCDM,skonb/ObjectiveCDM,jameshuynh/ObjectiveCDM,skonb/ObjectiveCDM,skonb/ObjectiveCDM,jameshuynh/ObjectiveCDM