Make tests pass

src/objective-c/GRPCClient/GRPCCall.m

@@ -249,7 +249,7 @@ const char *kCFStreamVarName = "grpc_cfstream";
     GRPCAssert(!self->_canceled, NSInternalInconsistencyException, @"Call arleady canceled.");
     GRPCAssert(!self->_finished, NSInternalInconsistencyException,
                @"Call is half-closed before sending data.");
-    if (self->_call) {
+    if (self->_pipe) {
       [self->_pipe writeValue:data];
     }
   });

src/objective-c/GRPCClient/private/GRPCChannel.m

@@ -281,15 +281,14 @@ static const NSTimeInterval kDefaultChannelDestroyDelay = 30;
 
 // This function should be called on _dispatchQueue.
 - (void)ref {
-  dispatch_sync(_dispatchQueue, ^{
+  _refcount++;
-    self->_refcount++;
+  if (_refcount == 1 && _lastDispatch != nil) {
-    if (self->_refcount == 1 && self->_lastDispatch != nil) {
+    _lastDispatch = nil;
-      self->_lastDispatch = nil;
   }
-  });
 }
 
 - (void)unref {
+  NSLog(@"unref");
   dispatch_async(_dispatchQueue, ^{
     GRPCAssert(self->_refcount > 0, NSInternalInconsistencyException, @"Illegal reference count.");
     self->_refcount--;

src/objective-c/GRPCClient/private/GRPCWrappedCall.m

@@ -325,7 +325,6 @@
 - (void)dealloc {
   if (_call) {
     grpc_call_unref(_call);
-    [_channel unref];
   }
   [_channel unref];
   _channel = nil;