Print Instance Output in Xcode Console

Question

I use the po command in the Xcode console to check the necessary information. Therefore, after I used po vc , I have the following:

 (lldb) po vc error: field '__FuncPtr' declared with incompatible types in different translation units ('void (*)(id)' vs. 'void (*)()') error: instance variable '_afterAppearance' declared with incompatible types in different translation units ('__block_literal_generic *' vs. '__block_literal_generic *') note: declared here with type 'void (*)()' note: declared here with type '__block_literal_generic *' error: 2 errors parsing expression 

po vc is my UIViewController. I checked it in this block of code after init:

 + (MyVC *)_new; { MyVC *vc = [[MyVC alloc] initWithNibName:nil bundle:nil]; return vc; }