iphone – 如何在按下按钮后显示UIPickerView动画？

我想按下按钮后动画我的UIPickerView.我已经将我的UIPickerView编码为隐藏在viewDidLoad上,而不是在按下按钮后隐藏,但它没有像默认情况下ModalViewController动画的动画.我只是希望我的UIPickerView动画就像ModalViewController默认动画一样.

我已经在网站和网络上进行过研究,但我似乎无法正确地进行研究.

这是我的代码：

#pragma mark - Picker View 

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return 4;
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    timersArray = [[NSMutableArray alloc] init];
    [timersArray addObject:@"No timer"];
    [timersArray addObject:@"15 seconds"];
    [timersArray addObject:@"30 seconds"];
    [timersArray addObject:@"60 seconds"];

    return [timersArray objectAtIndex:row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    if ([[timersArray objectAtIndex:row] isEqual:@"No timer"])
    {
        timerIndication.text = @"No timer selected";
        timersPickerView.hidden = YES;
        // Animation code to dismiss picker should go here
    }
    else if ([[timersArray objectAtIndex:row] isEqual:@"15 seconds"])
    {
        timerIndication.text = @"15 seconds selected";
        timersPickerView.hidden = YES;
        // Animation code to dismiss picker should go here
    }
    else if ([[timersArray objectAtIndex:row] isEqual:@"30 seconds"])
    {
        timerIndication.text = @"30 seconds selected";
        timersPickerView.hidden = YES;
        // Animation code to dismiss picker should go here
    }
    else if ([[timersArray objectAtIndex:row] isEqual:@"60 seconds"])
    {
        timerIndication.text = @"60 seconds selected";
        timersPickerView.hidden = YES;
        // Animation code to dismiss picker should go here
    }
}

#pragma mark - Delay method

// This is where Send button should be enabled
- (IBAction)selectTimer
{
    timersPickerView.hidden = NO;
    // Animation code to present picker view should go here
}

-(IBAction)button:(id)sender
{

   [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.6];
    CGAffineTransform transfrom = CGAffineTransformMakeTranslation(0,200);
    PickerView.transform = transfrom;
    PickerView.alpha = PickerView.alpha * (-1) + 1;
    [UIView commitAnimations];

}

PickerView.alpha = 0;    
[self.view addSubview:PickerView];