Using an undeclared identifier

Question

I am trying to set up a two-component collector and getting some errors that I commented on:

Implementation File:

#import "BIDDoubleComponentPickerViewController.h" @implementation BIDDoubleComponentPickerViewController @synthesize doublePicker; @synthesize fillingTypes; @synthesize breadTypes; - (IBAction)buttonPressed:(id)sender { NSInteger fillingRow = [doublePicker selectedRowInComponent:kFillingComponent]; // Use of undeclared identifier 'kFillingComponent' NSInteger breadRow = [doublePicker selectedRowInComponent:kBreadComponent]; // Use of undeclared identifier 'kBreadComponent' NSString *bread = [breadTypes objectAtIndex:breadRow]; NSString *filling = [fillingTypes objectAtIndex:fillingRow]; NSString *message = [[NSString alloc]initWithFormat:@"Your %@ on %@ bread will be right up", filling, bread]; UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Thank you for your order" message:message delegate:nil cancelButtonTitle:@"Great!" otherButtonTitles:nil]; [alert show]; } - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view from its nib. NSArray *fillingArray = [[NSArray alloc] initWithObjects:@"Ham", @"Turkey", @"Peanut Butter", @"Tuna Salad", @"Chicken Salad", @"Roast Beef", @"Vegemite", nil]; self.fillingTypes = fillingArray; NSArray *breadArray = [[NSArray alloc] initWithObjects:@"White", @"Whole Wheat", @"Rye", @"Sourdough Bread", @"Seven Grain", nil]; self.breadTypes = breadArray; } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // eg self.myOutlet = nil; self.doublePicker = nil; self.breadTypes = nil; self.fillingTypes = nil; } #pragma mark - View lifecycle - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } #pragma mark - #pragma mark Picker Data Source Methods - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { return 2; } - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { if (component == kBreadComponent) { // Use of undeclared identifier 'kBreadComponent' return [self.breadTypes.count]; // Expected identifier return [self.fillingTypes objectAtIndex:row]; // Use of undeclared identifier 'row' } } #pragma mark Picker Delegate Methods - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { if (component == kBreadComponent) { // Use of undeclared identifier 'kBreadComponent' return [self.breadTypes objectAtIndex:row]; return [self.fillingTypes objectAtIndex:row]; } } @end 

Interface File:

 #import <UIKit/UIKit.h> @interface BIDDoubleComponentPickerViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource> @property (strong, nonatomic) IBOutlet UIPickerView *doublePicker; @property (strong, nonatomic) NSArray *fillingTypes; @property (strong, nonatomic) NSArray *breadTypes; - (IBAction)buttonPressed:(id)sender; @end 

Answer 1

kBreadComponent and kFillingComponent not declared anywhere. If they are declared in the header file (.h), you need to #import it.

Answer 2

Your methods numberOfRowsInComponent and titleForRow are similar, and they are wrong: they have the following two unconditional return , which means that the second will never be executed.

 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { return self.breadTypes.count; } #pragma mark Picker Delegate Methods - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { if (component == kBreadComponent) { return [self.fillingTypes objectAtIndex:row]; } return nil; // Or something, empty string for example. Method requires to return a NSString, so you have to return at least nil; } 

However, you should find the kBreadComponent and kFillingComponent and #import file with their definitions.