Difference between ivar and global var

objc-variable.m

@implementation MyClass {
  // It is an ivar, or called member variable
  // Can NOT be initialized when defined.
  // Can be accessed with `self->_i`
  int _i; 
}

int i = 9; // Global variable, and can be initialized when defined.
@end
  
  
 // Another file
extern int i;
NSLog(@"%i", i);