Question

When I try to compile this I get this error. What do I need to add for the property declaration in the interface? If textBox is an instance variable, why does it need to be declared as a property?

ViewController.h

#import <UIKit/UIKit.h>

@interface TNRViewController : UIViewController {

    IBOutlet UITextField *textBox;
    IBOutlet UILabel *label;
}
- (IBAction)button:(id)sender;

@end

ViewController.m

#import "TNRViewController.h"

@implementation TNRViewController
@synthesize textBox;

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)dealloc {
    [textBox release];
    [label release];
    [super dealloc];
}
- (IBAction)button:(id)sender {
    NSString *Name = textBox.text;
    NSString *Output = Nil;
    Output = [[NSString alloc] initWithFormat:@"%@ says: Hello World!", Name];
    label.text = Output;
    [Output release];
}

- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
    [textBox resignFirstResponder];
    return YES;
}
@end

Answer 1

textBox needs to be declared as a property because you are @synthesizing it in your implementation.

You need to either:

1. Add the @property declaration for textBox in your interface.

2. OR, You could remove the @sythesize line from your implementation if you don’t plan on needing the setter/getter methods.