应用程序崩溃：以NSException类型的未捕获异常终止

Question

我正在使用Swift和Objective-C编写应用程序，当我在iPhone上运行测试应用程序时，一切正常，但当我尝试启动调用时，应用程序崩溃显示：

 *** First throw call stack:
   (0x181be11b8 0x18061855c 0x181be1100 0x182610eb8 0x100265a2c 0x187acbd30 0x187acbcb0 0x187ab6128 0x187acb59c 0x187acb0c4 0x187ac6328 0x187a96da0 0x18828075c 0x18827a130 0x181b8eb5c 0x181b8e4a4 0x181b8c0a4 0x181aba2b8 0x18356e198 0x187b017fc 0x187afc534 0x1002bc898 0x180a9d5b8)
 libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) terminating

这是按钮代码：

   - (IBAction)startCallButton:(id)sender {

TCallViewController *callViewController = [[TCallViewController alloc] init];
[self.navigationController pushViewController:callViewController animated:YES];
 NSString *handle = [[NSString alloc] initWithString:_handle];
 BOOL Video = _video;
 if ((handle = callViewController.handle) ){
 Video = callViewController.video;
[callManager startCallWithHandle:(handle) video:Video];

 }
   }

我该如何解决这个问题？