UIPickerView - 1st row selection does not call didSelectRow

Question

I have a UIPickerView on my UIView along with a UITextField. I am letting the user select a value from the picker or enter a custom va

Answer 1

Instead of "pushing" the value of the picker each time you make a selection with this code:

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

you should "pull it" when the user clicks the button (or other event you are using) using something similar to:

- (void)myAction:(id)sender
{

    NSInteger row = [myPicker selectedRowInComponent:0];
    selectedText = [myArray objectAtIndex:(NSUInteger)row];


}

For clearing the text: The UITextField class provides a built-in button for clearing the current text. So if the user does not want that text he can discard it.

myTextField.clearButtonMode = UITextFieldViewModeAlways; 

So in the script, will you check if the TextField has a value, if it does have a value u use the TextField, if it doesn't have a value, you pull the information from the Picker.

Answer 2

-(void)textFieldDidBeginEditing:(UITextField *)textField
{
    // Only for the text field with the picker
    if (textField == self.yourTextField && [textField length]!=0)
    {
        // Select the first row programmatically 
        [self.categoriesPicker selectRow:0 inComponent:0 animated:YES];
        // The delegate method isn't called if the row is selected programmatically
        [self pickerView:self.categoriesPicker didSelectRow:0 inComponent:0];
    }



}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    //Do all the stuff to populate the TextField
}

Answer 3

To overcome the didSelectRow not getting called in the UIPickerView when the user selected the first item in the list, you can use UITapGestureRecognizer. (Code example in Swift)

self.txtTransType = self.makeTextField(self.transType, placeHolder: "Check-in or Check-out")
self.txtTransType?.addTarget(self, action: "txtTransTypeEditing:", forControlEvents: UIControlEvents.EditingDidBegin)

func makeTextField(text: String?, placeHolder: String) -> UITextField {
    var textField = UITextField(frame: CGRect(x: 140, y: 0, width: 220.00, height: 40.00));
    textField.placeholder = placeHolder
    textField.text = text
    textField.borderStyle = UITextBorderStyle.Line
    textField.secureTextEntry = false;
    textField.delegate = self
    return textField
}

func txtTransTypeEditing(sender: UITextField) {
    var ttPickerView:UIPickerView = UIPickerView()
    ttPickerView.dataSource = self
    ttPickerView.delegate = self
    sender.inputView = ttPickerView

    let recognizer = UITapGestureRecognizer(target: self, action:Selector("handleTransTypePickerTap:"))
    recognizer.delegate = self
    ttPickerView.addGestureRecognizer(recognizer)
}

func handleTransTypePickerTap(recognizer: UITapGestureRecognizer) {
    let ttPickerView = recognizer.view as! UIPickerView
    let row = ttPickerView.selectedRowInComponent(0)
    self.txtTransType!.text = self.transTypeData[row]
}

Use the following link UIGestureRecognizer Tutorial: Getting Started to get tap recognizer to work (need to add UIGestureRecognizerDelegate) and following code

class TransactionViewController: UIViewController, UITextFieldDelegate,UIPickerViewDataSource,UIPickerViewDelegate, UIGestureRecognizerDelegate  { }

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

Answer 4

Can you programmatically select a row right after you instantiate the UIPickerView?

int firstRow = 0;
int firstOptionIndex = 0;
[myPickerView selectRow:firstRow inComponent:firstOptionIndex animated:NO];

That last line will trigger your pickerView:didSelectRow:inComponent delegate method.

In other words, that should set the value of the variable, wherever you are storing it (NSArray? not clear).

Answer 5

You can directly call delegate's method like

picker.delegate?.pickerView?(picker, didSelectRow: 0, inComponent: 0)