问如何在IOS 8的UIActionSheet中添加UIPickerView不起作用？

UIActionSheet *actionSheet;
NSString *pickerType;

- (void)createActionSheet {

    if (actionSheet == nil) {
        // setup actionsheet to contain the UIPicker
        actionSheet = [[UIActionSheet alloc] initWithTitle:@"Please select" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil];
        actionSheet.backgroundColor = [UIColor clearColor];

        UIToolbar *pickerToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 40)];
        pickerToolbar.barStyle = UIBarStyleBlackOpaque;
        [pickerToolbar sizeToFit];

        UIImageView *imageObj = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
        imageObj.image = [UIImage imageNamed:@"header.png"];
        [pickerToolbar addSubview:imageObj];

        UIButton *cancelBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        [cancelBtn addTarget:self action:@selector(pickerCancel:)forControlEvents:UIControlEventTouchDown];
        // [cancelBtn setImage:[UIImage imageNamed:@"btnInviteCancel.png"] forState:UIControlStateNormal];
        [cancelBtn setTitle:@"Cancel" forState:UIControlStateNormal];

        cancelBtn.frame = CGRectMake(7.0, 7.0, 65.0, 25.0);
        [pickerToolbar addSubview:cancelBtn];

        UIButton *doneBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        [doneBtn addTarget:self action:@selector(pickerDone:)forControlEvents:UIControlEventTouchDown];
        //[doneBtn setImage:[UIImage imageNamed:@"btnInviteDone.png"] forState:UIControlStateNormal];
        [doneBtn setTitle:@"Done" forState:UIControlStateNormal];
        doneBtn.frame = CGRectMake(258.0, 7.0, 55.0, 25.0);
        [pickerToolbar addSubview:doneBtn];

        [actionSheet addSubview:pickerToolbar];
        [pickerToolbar release];


        UIPickerView *chPicker = [[UIPickerView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 200.0)];
        chPicker.dataSource = self;
        chPicker.delegate = self;
        chPicker.showsSelectionIndicator = YES;
        [chPicker selectRow:0 inComponent:0 animated:YES];
        [actionSheet addSubview:chPicker];
        [chPicker release];

        [actionSheet showInView:self.view];
        [actionSheet setBounds:CGRectMake(0,0,320, 464)];
    }
}