IOS determines caller status Ctcallcenter code block does not perform problem resolution

The project needs to detect the status of the call, using the Ctcallcenter, in Appdelegate, the code is as follows:

? Ctcallcenter *callcenter = [[Ctcallcenter alloc] init];    Callcenter.calleventhandler = ^ (Ctcall *call) {                if ([call.callstate isequaltostring:ctcallstatedialing]) {                        NSLog (@ "Call dialing");                    }                if (call.callstate = = ctcallstateconnected) {                        NSLog (@ "Call Connected");                    }                if (call.callstate = = ctcallstatedisconnected) {                   }            };?

It is strange to do nothing at all .... Call to answer the hanging off God horse does not walk block.

Looking for half a day Niang Google also have no solution. And then actually thought,

Ctcallcenter *callcenter writes the member variable and then it's normal ...

In the original Arc mode, a block of code, Callcenter was released.

IOS determines caller status Ctcallcenter code block does not perform problem resolution