Specifying arrays for two identical picker components in Xcode

Question

Is this appropriate code for the arrays in a picker with two identical components? Or can both components somehow use the same arrays?

    - (void)viewDidLoad
{
    self.fromArray = [[NSArray alloc] initWithObjects:
                      @"Annual", @"Monthly", @"48/Year", @"SemiMonthly", @"BiWeekly", @"Weekly", @"Hourly", nil];

    self.fromValues = [[NSArray alloc] initWithObjects: 
                       [NSNumber numberWithFloat:1.0],
                       [NSNumber numberWithFloat:12.0], 
                       [NSNumber numberWithFloat:48.0],
                       [NSNumber numberWithFloat:24.0], 
                       [NSNumber numberWithFloat:26.0],
                       [NSNumber numberWithFloat:52.0], 
                       [NSNumber numberWithFloat:2080.0], nil];


    self.toArray = [[NSArray alloc] initWithObjects:
                      @"Annual", @"Monthly", @"48/Year", @"SemiMonthly", @"BiWeekly", @"Weekly", @"Hourly", nil];

    self.toValues = [[NSArray alloc] initWithObjects: 
                     [NSNumber numberWithFloat:1.0],
                     [NSNumber numberWithFloat:12.0], 
                     [NSNumber numberWithFloat:48.0],
                     [NSNumber numberWithFloat:24.0], 
                     [NSNumber numberWithFloat:26.0],
                     [NSNumber numberWithFloat:52.0], 
                     [NSNumber numberWithFloat:2080.0], nil];

Also, how would I properly format a calculation using values from both components and a Text Field? This is just not working.

I tried this, but I get undeclared identifier errors with the use of 'row'.

- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component
{
    if (component == 0) {
        return [fromArray objectAtIndex:row];
    }
    return [toArray objectAtIndex:row];
} 
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
      inComponent:(NSInteger)component {
}

- (IBAction)Convert:(id)sender {
    float valuein = [[fromValues objectAtIndex:row] floatValue];
    float valueout = [[toValues objectAtIndex:row] floatValue];
    float input = [inputText.text floatValue];
    float result = input * valuein / valueout;
    NSString *resultString = [[NSString alloc] initWithFormat: @"$ %@", [toArray objectAtIndex:row]];
    resultText.text = [NSString stringWithFormat:@"$%6.2f",result];
}

EDIT: Here is the current version of full .m file code, as requested below. I suspect there is a bit of unnecessary code. The only warning is Unused variable 'resultString'.

#import "PayFrequencyViewController.h"

@interface PayFrequencyViewController ()

@end

@implementation PayFrequencyViewController
@synthesize payPicker;
@synthesize toArray;
@synthesize fromArray;
@synthesize toValues;
@synthesize fromValues;
@synthesize resultText;
@synthesize inputText;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    self.fromArray = [[NSArray alloc] initWithObjects:
                      @"Annual", @"Monthly", @"48/Year", @"SemiMonthly", @"BiWeekly", @"Weekly", @"Hourly", nil];

    self.fromValues = [[NSArray alloc] initWithObjects: 
                       [NSNumber numberWithFloat:1.0],
                       [NSNumber numberWithFloat:12.0], 
                       [NSNumber numberWithFloat:48.0],
                       [NSNumber numberWithFloat:24.0], 
                       [NSNumber numberWithFloat:26.0],
                       [NSNumber numberWithFloat:52.0], 
                       [NSNumber numberWithFloat:2080.0], nil];

    self.toArray = self.fromArray;
    self.toValues =  self.fromValues;

    [super viewDidLoad];
    inputText.keyboardType = UIKeyboardTypeDecimalPad;
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
    self.toArray = nil;
    self.fromArray = nil;
    self.resultText = nil;
    self.inputText = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {

    return 2;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {

    if (component == 0) {
        return [fromArray count];
    }
    return [toArray count];
}

- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component
{
    if (component == 0) {
        return [fromArray objectAtIndex:row];
    }
    return [toArray objectAtIndex:row];
} 

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
      inComponent:(NSInteger)component {
    _row = row;
}

- (IBAction)Convert:(id)sender {
//    float valuein = [[fromValues text] floatValue];
//    float valueout = [[toValues text] floatValue];
//    [resultText setText:[NSString stringWithFormat:@"%6.2f", result]];
//    [inputText resignFirstResponder]; 
    float valuein = [[fromValues objectAtIndex:_row] floatValue];
    float valueout = [[toValues objectAtIndex:_row] floatValue];
    float input = [inputText.text floatValue];
    float result = input * valuein / valueout;
    NSString *resultString = [[NSString alloc] initWithFormat: @"$ %@", [toArray objectAtIndex:_row]];
    resultText.text = [NSString stringWithFormat:@"$%6.2f",result];
}

- (IBAction)Clear:(id)sender {
    inputText.text = @"";
    resultText.text = @"";
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
    [inputText resignFirstResponder];
}
@end

Answer 1

OK, there are a few things :

First, your arrays are leaking memory, since you alloc, init them without releasing them (unless you use ARC, in that case this is fine).

Second, if you want them to share the same array, why don't you do something like

 self.toArray = self.fromArray;
 self.toValues =  self.fromValues;

?

how would I properly format a calculation using values from both components and a Text Field?

You need to be more clear here, I don't understand what you're trying to do.

However, in your first chunk of code : at the time you try to use row it isn't defined. You might need to learn about variables and scope.

Why don't you create an instance variable _row in your class @interface

NSInteger _row;

and set that variable like

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
  inComponent:(NSInteger)component {
      _row = row;
 }

ant then, use _row afterward when you need it ?

As for the last chunk of code, what were you trying to achieve with [fromValues text] ?