Ipad – Unselected Symbol of Architecture I386: Apple Mach-O LINKE (ID) error

Undefined symbols for architecture i386:
"_OBJC_CLASS_$_ViewController", referenced from:
 objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

< /p>

I have this error

Undefined symbols for architecture i386:
"_OBJC_CLASS_$_ViewController", referenced from:
 objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation) 

How do you solve this problem? Please help me.

Find the ViewController.m file in the project and select it. 
Use the property inspector (Apple -Option-1) Make sure to add it to the target membership, no matter what the target may be. It needs to be ticked next to the target.