UIPickerView added to uitableviewcontroller.view won't rotate

Question

Hello folks. I have a UIPickerView as subview in a UITableViewController, which I want to slide up in place when a certain row is clicked. I have implemented the necessary dataSource and delegate methods, but the pickerview acts weirdly. It acts as if it were mechanically jammed, it cannot rotate properly, it just moves a little. If I try to spin it a few times I get this message in the debugger console:

SendDelegateMessage: delegate failed to return after waiting 10 seconds. main run loop mode: UITrackingRunLoopMode If you were not using the touch screen for this entire interval (which can prolong this wait), please file a bug.

I googled for this, to no avail. Anyway, here is the relevant code. As you may guess, this is a number picker (to choose a percentage value).

- (void)viewDidLoad {
     [super viewDidLoad];
     percentPicker  = [[UIPickerViewalloc] initWithFrame:CGRectMake(0,420, 320, 200)];
     percentPicker.delegate = self;
     percentPicker.dataSource = self;
     percentPicker.showsSelectionIndicator = YES;
     [self.view addSubview:percentPicker];
 }

- (void)viewWillAppear:(BOOL)animated {
     // sets the rows to the appropriate value
     // etc
}

- (void)startEditingPercentage {
     [UIView beginAnimations :nilcontext:NULL];
     [UIView setAnimationBeginsFromCurrentState:YES];
     [UIViewsetAnimationDuration:kPickerAnimationDuration ];
     percentPicker.transform = CGAffineTransformTranslate(CGAffineTransformIdentity, 0, -220.0);
     [UIViewcommitAnimations];
 }

- (void)stopEditingPercentage {
    NSLog(@"stopEditingPercentage");
    [UIView beginAnimations :nilcontext:NULL];
    [UIViewsetAnimationBeginsFromCurrentState:YES];
    [UIViewsetAnimationDuration:kPickerAnimationDuration];
    percentPicker.transform = CGAffineTransformIdentity;
    [UIView commitAnimations];
}

#pragma mark UIPickerView delegate and dataSource methods

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return4;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return10;
}

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component { 
    return44;
}

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
    UILabel *retval = (UILabel *)view;
    if (!retval) {
        retval= [[UILabel newLabelWithPrimaryColor :[UIColorblackColor ] selectedColor:[ UIColor blackColor] fontSize:22bold:YEStransparent:YES] autorelease];
    }
    retval.frame = CGRectMake(0, 0, 44, 44);
    retval.textAlignment = UITextAlignmentCenter;
    retval.backgroundColor = [UIColor clearColor];
    retval.text = [NSStringstringWithFormat:@"%i", row];
    if (component > 1 ) {
        // rows 2 and 3 are decimal, white on black
        retval.backgroundColor = [UIColor blackColor];
        retval.textColor = [UIColor whiteColor];
    }
    return retval;
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    NSString *selectedValue;
    selectedValue= [NSString stringWithFormat:@"%i%i.%i%i" ,[percentPickerselectedRowInComponent :0], [ percentPickerselectedRowInComponent: 1], [percentPickerselectedRowInComponent:2], [percentPickerselectedRowInComponent:3]];
    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    NSString *trimmedValue = [[formatter numberFromString:selectedValue] stringValue];
    percentValue.text = trimmedValue;
    [formatter release];
}

As you see, I use the transform property to move the picker in and out (down) my main view; the startEditing and stopEditing methods are triggered by selection in the teble view. Yet, for the debugging purposes, I eliminated these transitions , and left the picker on top of the table, but nothing changed. I also commented the didSelect method, but this also didn't change anything. By the way, the same picker-view construction code vorkw allright in another view of the same app. Any suggestion? Cheers,

Answer 1

You aren't really adding the picker to UITableView using the code in viewDidLoad. UITableView can only have controls/rows in UITableViewCells and these are specified in the cellForRowAtIndex method. We cannot add controls to UITableView like we do to UIView.

Try using a subclass of UIView instead and add the UITableView and the picker to this UIView subclass.

In case you want to use a UITableViewController subclass only, create a custom cell and add the picker to this custom cell. But then you won't be able to hide/unhide this cell if you add it statically. Then you'll have to use reloadData. I would suggest using the UIView subclass.

Answer 2

Hi! I have the same problem in mi app. But I'm putting the picker in one normal UIView. This View is called by a table and I try to put one picker and i can't scroll only tap to change the values :(

I use the same code in other views and wors perfect. I don't know who is wrong :(

(Sorry for my bad english...)