Classes/ThreeViewController.m

/*
     File: ThreeViewController.m 
 Abstract: The view controller for page three. 
  Version: 1.6 
  
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 */
 
#import "ThreeViewController.h"
 
NSString *kBadgeValuePrefKey = @"kBadgeValue";  // badge value key for storing to NSUserDefaults
 
@interface ThreeViewController () <UITextFieldDelegate>
 
@property (nonatomic, strong) UIBarButtonItem *doneButton;
@property (nonatomic, weak) IBOutlet UITextField *badgeField;
 
- (void)doneAction:(id)sender;
 
@end
 
@implementation ThreeViewController
 
@synthesize doneButton;
 
- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // set the badge value in our test field and tabbar item
    NSString *badgeValue = [[NSUserDefaults standardUserDefaults] stringForKey:kBadgeValuePrefKey];
    doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(doneAction:)];
    if (badgeValue.length != 0)
    {
        self.badgeField.text = badgeValue;
        self.navigationController.tabBarItem.badgeValue = self.badgeField.text;
    }
}
 
- (void)doneAction:(id)sender
{
    // dismiss the keyboard by resigning our badge edit field as first responder
    [self.badgeField resignFirstResponder];
    
    // set the badge value to our tab item (but only if a valid string)
    if (self.badgeField.text.length > 0)
    {
        // a value was entered,
        // because we are inside a navigation controller,
        // we must access its tabBarItem to set the badgeValue.
        self.navigationController.tabBarItem.badgeValue = self.badgeField.text;
    }
    else
    {
        // no value was entered
        self.navigationController.tabBarItem.badgeValue = nil;
    }
    
    [[NSUserDefaults standardUserDefaults] setValue:self.badgeField.text forKey:kBadgeValuePrefKey];
}
 
 
#pragma mark - UITextFieldDelegate
 
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    // user is starting to edit, add the done button to the navigation bar
    self.navigationItem.rightBarButtonItem = self.doneButton;
}
 
- (void)textFieldDidEndEditing:(UITextField *)textField
{
    /// user is done editing, remove the done button from the navigation bar
    self.navigationItem.rightBarButtonItem = nil;
}
 
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    BOOL result = YES;
    
    // restrict the maximum number of characters to 5
    if (textField.text.length == 5 && string.length > 0)
        result = NO;
    
    return result;
}
 
@end