UIPickerView doesn't "snap" to rows and moves out of bounds

Question

I have a problem with UIPickerView. Following a tutorial on YT I created a UIPickerView in a popover after tapping on a textfield.

Everything looks fine, but the UIPickerView acts kind of strange. If I just tap on a row i want to select, it rolls up/down normally to this specific row and makes a selection. But if I try to scroll with my finger it doesn't roll as smooth as it should with a momentum and it doesn't snap on any of the rows. It also doesn't make a selection, but it makes a sound like it does. Worst of all, the picker doesn't seem to care about the number of rows and I can roll up and down as far as I want, although there are no selectable rows anymore.

Here is my code.

decayStatesArray contains four simple String-objects. The UITextfield und the activeDecayString are used in the "donePressed"-methode.

The main function:

-(void)showPicker:(UITextField *)textField {

activeTextfield = textField;
//for the default sizes of a UIPickerView
decayStatePicker = [[UIPickerView alloc] init];

UIViewController *popOverContent = [[UIViewController alloc] init];
UIView *popOverView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [decayStatePicker frame].size.width, [decayStatePicker frame].size.height+44)];
decayStatePicker = [[UIPickerView alloc] initWithFrame:CGRectMake([popOverView frame].origin.x, [popOverView frame].origin.y + 44, 0, 0)];
pickerToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake([popOverView frame].origin.x, [popOverView frame].origin.y, [popOverView frame].size.width, 44)];

[decayStatePicker setDataSource:self];
[decayStatePicker setDelegate:self];
[decayStatePicker setShowsSelectionIndicator:YES];
[decayStatePicker selectRow:0 inComponent:0 animated:YES];

//Create Toolbar
[pickerToolbar setBarStyle:UIBarStyleBlackTranslucent];
UIBarButtonItem *flexibleSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleBordered target:self action:@selector(donePressed)];
UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithTitle:@"Cancel" style:UIBarButtonItemStyleBordered target:self action:@selector(cancelPressed)];
[pickerToolbar setItems:[NSArray arrayWithObjects:flexibleSpace, doneButton, cancelButton, nil]];

[popOverView addSubview:decayStatePicker];
[popOverView addSubview:pickerToolbar];
[popOverContent setView:popOverView];

pickerPopoverController = [[UIPopoverController alloc] initWithContentViewController:popOverContent];
pickerPopoverController.popoverContentSize = CGSizeMake([popOverView frame].size.width, [popOverView frame].size.height);
[pickerPopoverController presentPopoverFromRect:[textField frame] inView:[self view] permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}

The delegate methodes:

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

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:  (NSInteger)component {
    return [decayStatesArray count];
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    return [decayStatesArray objectAtIndex:row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    if ([pickerView isEqual:decayStatePicker]) {
        NSLog(@"The Picker is: %@", pickerView);
        NSLog(@"The item is: %@", [decayStatesArray objectAtIndex:row]);
    }
    activeDecayString = [decayStatesArray objectAtIndex:row];
}