First, conform the class to the UIGestureRecognizerDelegate protocol

Then, in the view setup:

UITapGestureRecognizer *tapToSelect = [[UITapGestureRecognizer alloc]initWithTarget:self
                                                                                 action:@selector(tappedToSelectRow:)];
tapToSelect.delegate = self;
[self.pickerView addGestureRecognizer:tapToSelect];

And elsewhere:

#pragma mark - Actions

- (IBAction)tappedToSelectRow:(UITapGestureRecognizer *)tapRecognizer
{
    if (tapRecognizer.state == UIGestureRecognizerStateEnded) {
        CGFloat rowHeight = [self.pickerView rowSizeForComponent:0].height;
        CGRect selectedRowFrame = CGRectInset(self.pickerView.bounds, 0.0, (CGRectGetHeight(self.pickerView.frame) - rowHeight) / 2.0 );
        BOOL userTappedOnSelectedRow = (CGRectContainsPoint(selectedRowFrame, [tapRecognizer locationInView:self.pickerView]));
        if (userTappedOnSelectedRow) {
            NSInteger selectedRow = [self.pickerView selectedRowInComponent:0];
            [self pickerView:self.pickerView didSelectRow:selectedRow inComponent:0];
        }
    }
}

#pragma mark - UIGestureRecognizerDelegate

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return true;
}

Nikolay s answer in Swift 4:

First, add a UITapGestureRecognizer to your UIPickerView in viewDidLoad() and let your UIViewController conform to the UIGestureRecognizerDelegate.

let tap = UITapGestureRecognizer(target: self, action: #selector(pickerTapped))
tap.delegate = self
self.pickerView.addGestureRecognizer(tap)

Add this function which calls your UIPickerViewDelegate when a tap on a row has been detected:

@objc func pickerTapped(tapRecognizer: UITapGestureRecognizer) {
    if tapRecognizer.state == .ended {
        let rowHeight = self.pickerView.rowSize(forComponent: 0).height
        let selectedRowFrame = self.pickerView.bounds.insetBy(dx: 0, dy: (self.pickerView.frame.height - rowHeight) / 2)
        let userTappedOnSelectedRow = selectedRowFrame.contains(tapRecognizer.location(in: self.pickerView))
        if userTappedOnSelectedRow {
            let selectedRow = self.pickerView.selectedRow(inComponent: 0)
            pickerView(self.pickerView, didSelectRow: selectedRow, inComponent: 0)
        }
    }
}

Add the shouldRecognizeSimultaneouslyWith method from UIGestureRecognizerDelegate:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Nikolay s Answer with Swift:

let tap = UITapGestureRecognizer(target: self, action: #selector(OCAccountSettingsViewController.pickerTapped(_:)))
tap.cancelsTouchesInView = false
tap.delegate = self
pickerView.addGestureRecognizer(tap)

important let your viewController confirm the UIGestureRecognizerDelegate otherwise handler won t fire:

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true}

the last step will be the handler for tap event:

func pickerTapped(tapRecognizer:UITapGestureRecognizer)
{
    if (tapRecognizer.state == UIGestureRecognizerState.Ended)
    {
      let rowHeight : CGFloat  = self.pickerView.rowSizeForComponent(0).height
      let selectedRowFrame: CGRect = CGRectInset(self.pickerView.bounds, 0.0, (CGRectGetHeight(self.pickerView.frame) - rowHeight) / 2.0 )
      let userTappedOnSelectedRow = (CGRectContainsPoint(selectedRowFrame, tapRecognizer.locationInView(pickerView)))
      if (userTappedOnSelectedRow)
      {
        let selectedRow = self.pickerView.selectedRowInComponent(0)
        //do whatever you want here
      }
    }
  }

Solution touchesBegan: / touchesEnded: worked fine for me when using iOS 4.2/4.3, but they stopped working with iOS. Finally I got this solution which may be helpful: using tap gesture recognition.

    IBOutlet UIPickerView *picker;

    [picker addGestureRecognizer:
        [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(pickerTapped:)] autorelease]
    ];

In this case when a user taps on picker view, the selector

    -(void)pickerTapped:(UIGestureRecognizer *)gestureRecognizer

is invoked. Worked for me on both iOS 4.2+ / 5.0

Here s swift code for figuring out if user tapped inside the selected row or not. I just converted obj-c code from Nikolay s answer.

func pickerTapped(sender: UITapGestureRecognizer){
    let rowHeight = self.rowSizeForComponent(0).height
    let selectedRowFrame = CGRectInset(self.bounds, 0.0, (CGRectGetHeight(self.frame) - rowHeight) / 2.0)
    let userTappedOnSelectedRow = CGRectContainsPoint(selectedRowFrame, sender.locationInView(self))
    if( userTappedOnSelectedRow ){
        // .. your action here ..
    }
}

I solved this by subclassing a common superview and intercepting the touch events before sending them forward. In interface builder, I also added a button where the selector area is, attached an action to the touch up event, and sent the button to "the back" (that s very important so it doesn t return itself in hitTest). The most relevant code is below. It could be improved for more complicated, like multitouch, cases.

    @implementation InterceptorView


-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
 UITouch *t=[touches anyObject];
 CGPoint p=[t locationInView:button];
 if ([button hitTest:p withEvent:event]) 
  started_in_button=YES;
 [hitView touchesBegan:touches withEvent:event];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
 [hitView touchesMoved:touches withEvent:event];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
 UITouch *t=[touches anyObject];
 CGPoint p=[t locationInView:button];
 if ([button hitTest:p withEvent:event] && started_in_button) {
  started_in_button=NO;
  [button sendActionsForControlEvents:UIControlEventTouchUpInside];
 }
 [hitView touchesEnded:touches withEvent:event];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
 [hitView touchesCancelled:touches withEvent:event];
}

- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
 hitView = [super hitTest:point withEvent:event];
 return self;
}

Here s Nikolay s trick in Swift v3:

First, make your UIViewController implement protocol UIGestureRecognizerDelegate, and add this method to it:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Then, apply a UITapGestureRecognizer on the picker, and when your target is called, call the following extension method:

extension UIPickerView {
    func pickerTapped(nizer: UITapGestureRecognizer, onPick: @escaping (Int) -> ()) {
        if nizer.state == .ended {
            let rowHeight = self.rowSize(forComponent: 0).height
            let selectedRowFrame = self.bounds.insetBy(dx: 0, dy: (self.frame.height - rowHeight) / 2)

            // check if begin and end tap locations both fall into the row frame:
            if selectedRowFrame.contains(nizer.location(in: self)) &&
                   selectedRowFrame.contains(nizer.location(ofTouch: 0, in: self)) {
                onPick(self.selectedRow(inComponent: 0))
            }
        }
    }
}

1. Add a tapGestureRecognizer to the pickerView as already suggested

2. Provide views for the picker rows, not the title, via

   -(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view

3. In the gesture s callback method do this

-(void)pickerTapped:(UIGestureRecognizer *)gestureRecognizer {

UIPickerView * pv = (id)gestureRecognizer.view;
UIView * selView = [pv viewForRow:[pv selectedRowInComponent:0]
                     forComponent:0];
CGPoint touchPoint = [gestureRecognizer locationInView:selView];
BOOL tapOnSelection = CGRectContainsPoint(selView.bounds, touchPoint);

if (tapOnSelection) ...

}

I think is more elegant then doing pixel math