How to set a default Value of a UIPickerView - ios

Question

I have a problem with my UIPickerView.
I have 3 values in it EU AP and NA.
When I start the app EU seems to be selected but when I make a NSLog(#"%#", [regions objectAtIndex:row]); I only get back (null),
now when I touch the UIPickerView the EU value is selected and I get "EU" back from a NSLog.
My question is:
How can I define a default value which is selected (not only the label) when the user only starts the app and touches nothing.
Edit: Here is my code to get the selected item:
#pragma mark -
#pragma mark PickerView DataSource
- (NSInteger)numberOfComponentsInPickerView:
(UIPickerView *)pickerView
{
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component
{
return [regions count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component
{
return [regions objectAtIndex:row];
}
#pragma mark -
#pragma mark PickerView Delegate
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
inComponent:(NSInteger)component
{
selectedRegion = [[NSString alloc] initWithFormat:
#"%#", [regions objectAtIndex:row]];
NSLog(#"%#", selectedRegion);
}

Answer 1

TL:DR version:
//Objective-C
[self.picker selectRow:2 inComponent:0 animated:YES];
//Swift
picker.selectRow(2, inComponent:0, animated:true)
Either you didn't set your picker to select the row (which you say you seem to have done but anyhow):
- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated
OR you didn't use the the following method to get the selected item from your picker
- (NSInteger)selectedRowInComponent:(NSInteger)component
This will get the selected row as Integer from your picker and do as you please with it.
This should do the trick for yah. Good luck.
Anyhow read the ref:
https://developer.apple.com/documentation/uikit/uipickerview
EDIT:
An example of manually setting and getting of a selected row in a UIPickerView:
the .h file:
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>
{
UIPickerView *picker;
NSMutableArray *source;
}
#property (nonatomic,retain) UIPickerView *picker;
#property (nonatomic,retain) NSMutableArray *source;
-(void)pressed;
#end
the .m file:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize picker;
#synthesize source;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return YES;
}
- (void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.view.backgroundColor = [UIColor yellowColor];
self.source = [[NSMutableArray alloc] initWithObjects:#"EU", #"USA", #"ASIA", nil];
UIButton *pressme = [[UIButton alloc] initWithFrame:CGRectMake(20, 20, 280, 80)];
[pressme setTitle:#"Press me!!!" forState:UIControlStateNormal];
pressme.backgroundColor = [UIColor lightGrayColor];
[pressme addTarget:self action:#selector(pressed) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:pressme];
self.picker = [[UIPickerView alloc] initWithFrame:CGRectMake(20, 110, 280, 300)];
self.picker.delegate = self;
self.picker.dataSource = self;
[self.view addSubview:self.picker];
//This is how you manually SET(!!) a selection!
[self.picker selectRow:2 inComponent:0 animated:YES];
}
//logs the current selection of the picker manually
-(void)pressed
{
//This is how you manually GET(!!) a selection
int row = [self.picker selectedRowInComponent:0];
NSLog(#"%#", [source objectAtIndex:row]);
}
- (NSInteger)numberOfComponentsInPickerView:
(UIPickerView *)pickerView
{
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component
{
return [source count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component
{
return [source objectAtIndex:row];
}
#pragma mark -
#pragma mark PickerView Delegate
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
inComponent:(NSInteger)component
{
// NSLog(#"%#", [source objectAtIndex:row]);
}
#end
EDIT for Swift solution (Source: Dan Beaulieu's answer)
Define an Outlet:
#IBOutlet weak var pickerView: UIPickerView! // for example
Then in your viewWillAppear or your viewDidLoad, for example, you can use the following:
pickerView.selectRow(rowMin, inComponent: 0, animated: true)
pickerView.selectRow(rowSec, inComponent: 1, animated: true)
If you inspect the Swift 2.0 framework you'll see .selectRow defined as:
func selectRow(row: Int, inComponent component: Int, animated: Bool)
option clicking .selectRow in Xcode displays the following:

Answer 2

This is How to set a default Value of a UIPickerView
[self.picker selectRow:4 inComponent:0 animated:YES];

Answer 3

Swift solution:
Define an Outlet:
#IBOutlet weak var pickerView: UIPickerView! // for example
Then in your viewWillAppear or your viewDidLoad, for example, you can use the following:
pickerView.selectRow(rowMin, inComponent: 0, animated: true)
pickerView.selectRow(rowSec, inComponent: 1, animated: true)
If you inspect the Swift 2.0 framework you'll see .selectRow defined as:
func selectRow(row: Int, inComponent component: Int, animated: Bool)
option clicking .selectRow in Xcode displays the following:

Answer 4

I too had this problem. But apparently there is an issue of the order of method calls. You must call:
[self.picker selectRow:2 inComponent:0 animated:YES];
after calling
[self.view addSubview:self.picker];

Answer 5

You have to send
- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated
to the picker view before it appears. The documentation states that the method selectedRowInComp... will give -1, thus it is possible that the picker view is in a state with no selected row. It turns out to be in that state when created.

Answer 6

In normal case, you can do something like this in viewDidLoad method;
[_picker selectRow:1 inComponent:0 animated:YES];
In my case, I'd like to fetch data from api server and display them onto UIPickerView then I want the picker to select the first item by default.
The UIPickerView will look like it selected the first item after it was created, but when you try to get the selected index by using selectedRowInComponent, you will get NSNull.
That's because it detected nothing changed by the user (select 0 from 0 ).
Following is my solution (in viewWillAppear, after I fetched the data)
[_picker selectRow:1 inComponent:0 animated:NO];
[_picker selectRow:0 inComponent:0 animated:NO];
Its a bit dirty, but dont worry, the UI rendering in iOS is very fast ;)

Answer 7

For example: you populated your UIPickerView with array values, then you wanted
to select a certain array value in the first load of pickerView like "Arizona".
Note that the word "Arizona" is at index 2. This how to do it :) Enjoy coding.
NSArray *countryArray =[NSArray arrayWithObjects:#"Alabama",#"Alaska",#"Arizona",#"Arkansas", nil];
UIPickerView *countryPicker=[[UIPickerView alloc]initWithFrame:self.view.bounds];
countryPicker.delegate=self;
countryPicker.dataSource=self;
[countryPicker selectRow:2 inComponent:0 animated:YES];
[self.view addSubview:countryPicker];

Answer 8

In case someone is still looking answer to this old question in Swift, here is what worked for me. None of the above answers worked as I had to select the first row in viewDidLoad.
self.pickerView.delegate?.pickerView?(self.pickerView, didSelectRow: 0, inComponent: 0)
Hope this helps.