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Asked: 2026-05-11T01:45:55+00:00

I have a UIPickerView as subview in a UITableViewController, which I want to slide

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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,

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  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.

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