To add placeholder UITextView first take outlet of UITextField
ex- @property (weak, nonatomic) IBOutlet UITextView *yourTextView;
Then follow these steps

1. In viewDidLoad add these line of code

 self.yourTextView.text = @Please type here.;
    self.yourTextView.textColor = [UIColor lightGrayColor];
    self.yourTextView.delegate = self;

2. Place this code inside delegate method of UITextViewDelegate

- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
    self.yourTextView.text = @; //remove placeholder text as user start typing.
    self.yourTextView.textColor = [UIColor grayColor];
    return YES;
}

-(void) textViewDidChange:(UITextView *)textView
{
       if(self.yourTextView.text.length == 0)
     {
        self.yourTextView.textColor = [UIColor lightGrayColor];
        self.yourTextView.text = @Please type here.; //put placeholder text if user hasnt type any character.
        [self.yourTextView resignFirstResponder];
    }
}