Determine which row was clicked in UIPickerView

Problem

Recently I decided to pre-paint the interface of my application with the UIPickerView element, but I was not completely satisfied with what the standard set of tools offered me, namely: scroll it so that the desired element becomes under “Selection Indicator” and then perform some action. I needed to send a message with the necessary parameters by clicking on any line. So I decided to customize UIPickerView by attaching a UITapGestureRecogniser to it.

Decision

Below I will describe step by step the order of my actions. I work with the UIViewController subclass in which the UIPickerViewDelegate and UIPickerViewDataSource protocols are declared.

1. Add UITapGestureRecogniser to UIPickerView:
   
   

   UITapGestureRecognizer *tapgesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(whereAreYouTappedOnPicker:)]; [self.pickerView addGestureRecognizer:tapgesture]; 

   
   ')
   This action is performed in the viewDidLoad: function. whereAreYouTappedOnPicker: is the selector that will be called when you click on the picker and calculate which line was pressed.
   
   
2. We declare whereAreYouTappedOnPicker: in the header (.h file) of your UIViewController subclass.
   
   - (void) whereAreYouTappedOnPicker: (UIGestureRecognizer *) gestureRecognizer;
   
   
3. We write the implementation of the function that we declared earlier (we do it in the .m file).
   
   

    -(void)whereAreYouTappedOnPicker:(UIGestureRecognizer *)gestureRecognizer { //     UIPickerView CGPoint tapCoordinate = [gestureRecognizer locationInView:self.pickerView]; //    UIPickerView.    5          CGFloat heightOfPickerRow = self.pickerView.frame.size.height/5; //          NSInteger rowForSelectionIndicator =[self.pickerView selectedRowInComponent:0]; //           "Selection Indicator" if (tapCoordinate.y<heightOfPickerRow) { //         //        if ([self.pickerView selectedRowInComponent:0] > 1) rowForSelectionIndicator -=2; else rowForSelectionIndicator = -1; //    } else if (tapCoordinate.y<2*heightOfPickerRow) { //         //        if ([self.pickerView selectedRowInComponent:0] > 0) rowForSelectionIndicator -=1; else rowForSelectionIndicator = -1; //    } else if (tapCoordinate.y<3*heightOfPickerRow) { //        ,      "Selection Indicator" //  ,       rowForSelectionIndicator = [self.pickerView selectedRowInComponent:0]; } else if (tapCoordinate.y<4*heightOfPickerRow) { //         //        if ([self.pickerView selectedRowInComponent:0] < ([self.pickerView numberOfRowsInComponent:0]-1)) rowForSelectionIndicator +=1; else rowForSelectionIndicator = -1; //    } else { //         //        if ([self.pickerView selectedRowInComponent:0] < ([self.pickerView numberOfRowsInComponent:0]-2)) rowForSelectionIndicator += 2; else rowForSelectionIndicator = -1; //    } //     -       if (rowForSelectionIndicator!=-1) { //      // -  didSelectRow            . [self.pickerView selectRow:rowForSelectionIndicator inComponent:0 animated:YES]; //     [self customPickerView:self.pickerView didSelectRow:rowForSelectionIndicator inComponent:0 asResultOfTap:YES]; } } 

   
   
   Next, we need to provide for two cases: when the user scrolls the picker and when the user clicks on the desired line. We need this then, that didSelectRow: does not respond to scrolling with the help of the code, here we need the “other function”
   
   And so, we will have two events:
   
   1. When the user scrolls the piker, the didSelectRow method is called: in which the customPickerView: method is called and the index of the row that is under the “Selection Indicator” is passed as a parameter.
   2. When the user clicks on the desired line, the whereAreYouTappedOnPicker method is called: in which the customPickerView: method is called and the index of the line that was clicked is passed as a parameter.
   
   Method code didSelectRow:
   
   

    - (void)pickerView:(UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent:(NSInteger)component { [self customPickerView:pickerView didSelectRow:row inComponent:component asResultOfTap:NO]; } 

   
   
   
4. We declare the customPickerView: function in the header.
   
   

    -(void)customPickerView:(UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent:(NSInteger)component asResultOfTap:(bool)userTapped; 

   
   
   
5. Writing the implementation of the customPickerView function: in the .m file
   
   

    - (void)customPickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component asResultOfTap:(bool)userTapped { if (userTapped) //       { NSLog(@"  %i", row); } else //       "Selection Indicator"   { NSLog(@" %i", row); } } 

   
   

Problems

Sometimes when you quickly click on the picker selectedRow becomes equal to -1. When I click on the line, I move to the new View, so this option suits me.