I need to add a left bar button item in my app that looks like system back button, but is not the system back button, since it will appear on view controller that is the only vc
Try this:
// After you create and place your backButton:
UILabel* arrowLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 10, 20, 20)];
arrowLabel.text = @"<";
arrowLabel.textColor = [backButton titleColorForState:UIControlStateNormal];
arrowLabel.transform = CGAffineTransformMakeScale(1,2);
[backButton addSubview:arrowLabel];
If addSubview gives you trouble, try
[backButton insertSubview:arrowLabel atIndex:0];