UIPickView的显示与消失方法

//PickerView appear
-(void)ShowPickerView:(UIPickerView*)PickerViewTag
{
    if(PickerViewTag.superview==nil)
    {
        [self.view.window addSubview:PickerViewTag];
        CGRect screenRect=[[UIScreen mainScreen]applicationFrame];
        CGSize pickSize=[PickerViewTag sizeThatFits:CGSizeZero];
        CGRect startRect=CGRectMake(0.0, screenRect.origin.y+screenRect.size.height, pickSize.width, pickSize.height);
        PickerViewTag.frame=startRect;
        CGRect pickRect=CGRectMake(0.0, screenRect.origin.y+screenRect.origin.y+screenRect.size.height-pickSize.height, pickSize.width,pickSize.height);
       
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationDelegate:self];
        PickerViewTag.frame=pickRect;
        CGRect newFrame=self.view.frame;
        newFrame.size.height-=PickerViewTag.frame.size.height;
        self.tableView.frame=newFrame;
        [UIView commitAnimations];
    }
   
}
//PickerView Disappear
-(void)PickerViewDisappear:(UIPickerView *)PickerViewTag
{
    CGRect screenRect = [[UIScreen mainScreen] applicationFrame];
    CGRect endFrame=PickerViewTag.frame;
    endFrame.origin.y=screenRect.origin.y+screenRect.size.height;
   
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(slideDown:)];
    PickerViewTag.frame=endFrame;
    CGRect newFrame = self.tableView.frame;
    newFrame.size.height+=PickerViewTag.frame.size.height;
   
    self.tableView.frame=newFrame;
       
    // deselect the current table row
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
    [self.tableView deselectRowAtIndexPath:indexPath animated:YES];
    [PickerViewTag removeFromSuperview];
}