UITextField의 외곽선을 이미지로 했을 때, 고민하게 되는 문제.
UIView *paddingView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 5, 20)];
textField.leftView = paddingView;
textField.leftViewMode = UITextFieldViewModeAlways;http://stackoverflow.com/questions/3727068/set-padding-for-uitextfield-with-uitextborderstylenone
