Error de aserción en - [UIPickerTableView _createPreparedCellForGlobalRow: withIndexPath:], /SourceCache/UIKit_Sim/UIKit-2903.2/UITableView.m:7768

Estoy intentando mostrar UIPickerView con UIToolBar pero obtengo un error.

Aquí está mi código -

CGRect toolbarTargetFrame = CGRectMake(0, self.view.bounds.size.height-216-44, 320, 44);
CGRect datePickerTargetFrame = CGRectMake(0, self.view.bounds.size.height-216, 320, 216);

UIView *darkView = [[UIView alloc] initWithFrame:self.view.bounds];
darkView.alpha = 0;
darkView.backgroundColor = [UIColor blackColor];
darkView.tag = 9;
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissDatePicker:)];
[darkView addGestureRecognizer:tapGesture];
[self.view addSubview:darkView];

UIDatePicker *picker = [[UIDatePicker alloc] init];
picker.autoresizingMask = UIViewAutoresizingFlexibleWidth;
picker.datePickerMode = UIDatePickerModeDate;
[picker addTarget:self action:@selector(dueDateChanged:) forControlEvents:UIControlEventValueChanged];
[picker setFrame:CGRectMake(0,235,320,120)];
picker.backgroundColor = [UIColor blackColor];
[self.view addSubview:picker];

UIToolbar *toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, self.view.bounds.size.height, 320, 44)];
toolBar.tag = 11;
toolBar.barStyle = UIBarStyleBlackTranslucent;

UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil] ;
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissDatePicker:)];

[toolBar setItems:@[spacer, doneButton]];
[self.view addSubview:toolBar];

[UIView beginAnimations:@"MoveIn" context:nil];
toolBar.frame = toolbarTargetFrame;
picker.frame = datePickerTargetFrame;
darkView.alpha = 0.5;
[UIView commitAnimations];

Obteniendo error en esta línea -

picker.frame = datePickerTargetFrame;

Esto es error

*** Assertion failure in -[UIPickerTableView _createPreparedCellForGlobalRow:withIndexPath:], /SourceCache/UIKit_Sim/UIKit-2903.2/UITableView.m:7768
2013-10-03 13:43:12.688 Mistoh Beta 1[7228:a0b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource is not set'

libc++abi.dylib: terminating with uncaught exception of type NSException

Por favor ayúdame. Gracias de antemano.

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