使用下面的代码我得到了这个错误:Cannotconvertvalueoftype'inoutNSError?'(aka'inoutOptional')toexpectedargumenttype'()'在这行代码中:ifdevice.lockForConfiguration(&error)这是其余的代码:funcfocusWithMode(focusMode:AVCaptureFocusMode,exposureMode:AVCaptureExposureMode,point:CGPoint,monitorSubjectAreaChange:Bool){dispatch_async(s