QThread communicate threadsafe

[Ini]

I know it's not threadsafe to call a function of another thread in Mainthread. Is it allowed to call a signal form another thread without any problems? Lets say this code is in MainWindow:

MainWindow.cpp
thread->moveTOThread(obj); 
emit obj->Signal();

MainWindow.cpp
thread->moveTOThread(obj); 
emit obj->Signal();

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or is this the way to go:

Obj.h
signals:
void testSignal(); 
public slots:
void Func();
 
MainWindow.h
void testSignal(); 
 
MainWindow.cpp
thread->moveTOThread(obj); 
connect(this,SIGNAL(testSignal()),obj,SIGNAL(testSignal()));
emit testSignal(); 
 
Obj.cpp
connect(this,SIGNAL(testSignal()),this,SLOT(Func()));

Obj.h
signals:
void testSignal(); 
public slots:
void Func();

MainWindow.h
void testSignal(); 

MainWindow.cpp
thread->moveTOThread(obj); 
connect(this,SIGNAL(testSignal()),obj,SIGNAL(testSignal()));
emit testSignal(); 

Obj.cpp
connect(this,SIGNAL(testSignal()),this,SLOT(Func()));

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thank you