Question

Is the UIPicker that pops up from the bottom of the screen when an action is called just a basic UIPickerView that is coordinated in a certain way? (Like a UIActionSheet?) How would I implement that?

Answer 1

Here’s animation code, that I use:

- (void)animateDatePicker:(BOOL)show {
    CGRect screenRect = self.frame;
    CGSize pickerSize = [self.datePickerView sizeThatFits:CGSizeZero];
    CGRect startRect = CGRectMake(0.0,
                                  screenRect.origin.y + screenRect.size.height,
                                  pickerSize.width, pickerSize.height);

    CGRect pickerRect = CGRectMake(0.0,
                                   screenRect.origin.y + screenRect.size.height - pickerSize.height,
                                   pickerSize.width,
                                   pickerSize.height);

    self.datePickerView.frame = pickerRect;
    self.backgroundColor = UIColorMakeRGBA( 64, 64, 64, 0.7f - (int)show * 0.7f );

    if ( show ) {
        self.datePickerView.frame = startRect;
        [self.parentViewController addSubviewToWindow:self];
    }

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.3f];
    [UIView setAnimationDelegate:self];

    self.backgroundColor = UIColorMakeRGBA( 64, 64, 64, 0.0f + (int)show * 0.7f );

    if ( show ) {
        self.datePickerView.frame = pickerRect;
    } else {
        [UIView setAnimationDidStopSelector:@selector(slideDownDidStop)];
        self.datePickerView.frame = startRect;
    }

    [UIView commitAnimations];  
}

datePickerView is a view, that contains DatePicker:

self.datePickerView = [[UIView alloc] initWithFrame:CGRectMake(0.0, 174.0, 320.0, 286.0)];
self.datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0.0, 70.0, 320.0, 216.0)];
[self.datePicker setDatePickerMode:UIDatePickerModeDate];
[self.datePicker addTarget:self action:@selector(pickerValueChanged:) forControlEvents:UIControlEventValueChanged];
[self.datePickerView addSubview:self.datePicker];

parentViewController should implement addSubviewToWindow method:

- (void)addSubviewToWindow:(UIView *)addView {
    [self.view addSubview:addView];
}

UIColorMakeRGBA:

#define UIColorMakeRGBA(nRed, nGreen, nBlue, nAlpha) [UIColor colorWithRed:(nRed)/255.0f green:(nGreen)/255.0f blue:(nBlue)/255.0f alpha:nAlpha]

slideDownDidStop is a method, that will be called after datePicker slide down successfully.

So, just to summarize – you have MyViewController, that have

MyDatePickerView *myDatePicker;

field.

MyDatePickerView is a custom class, that have UIDatePicker *datePicker field, MyViewController *parentViewController and animateDatePicker method.

When you perform some action on MyViewController (for example, UIControlEventTouchUpInside for some button), you should invoke

[myDatePicker animateDatePicker:YES];

Please let me know if you have questions.

UPDATE:
Here’s a small example.