Navigation Controller inside a Tab Bar Controller

When you are using a Tab View controller based project it doesn’t come with a navigation stack by default. So if you would like have a navigation view on each tab, with a tab bar and back button, when navigating in the stack, here is the code to do so. All you need to do is modify the function: didFinishLaunchingWithOptions.

Standard Code

This is the standard code that you get when you create a tab view project:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.

UIViewController *viewController1, *viewController2, *viewController3;
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
viewController1 = [[[MainViewController alloc] initWithNibName:@”MainViewController_iPhone” bundle:nil] autorelease];
viewController2 = [[[SecondViewController alloc] initWithNibName:@”SecondViewController_iPhone” bundle:nil] autorelease];
viewController3 = [[[SettingsViewController alloc] initWithNibName:@”SettingsViewController_iPhone” bundle:nil] autorelease];
} else {
viewController1 = [[[MainViewController alloc] initWithNibName:@”MainViewController_iPad” bundle:nil] autorelease];
viewController2 = [[[SecondViewController alloc] initWithNibName:@”SecondViewController_iPad” bundle:nil] autorelease];
viewController3 = [[[SettingsViewController alloc] initWithNibName:@”SettingsViewController_iPad” bundle:nil] autorelease];
}
self.tabBarController = [[[UITabBarController alloc] init] autorelease];
self.tabBarController.viewControllers = @[viewController1, viewController2, viewController3];
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];
return YES;
}

Modified Function to add a Navigation Stack

All you simply need to do is embed the main view controllers for each tab inside a navigation view controller.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.

UINavigationController *navController1, *navController2, *navController3;

UIViewController *viewController1, *viewController2, *viewController3;
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
viewController1 = [[[MainViewController alloc] initWithNibName:@”MainViewController_iPhone” bundle:nil] autorelease];
viewController2 = [[[SecondViewController alloc] initWithNibName:@”SecondViewController_iPhone” bundle:nil] autorelease];
viewController3 = [[[SettingsViewController alloc] initWithNibName:@”SettingsViewController_iPhone” bundle:nil] autorelease];
} else {
viewController1 = [[[MainViewController alloc] initWithNibName:@”MainViewController_iPad” bundle:nil] autorelease];
viewController2 = [[[SecondViewController alloc] initWithNibName:@”SecondViewController_iPad” bundle:nil] autorelease];
viewController3 = [[[SettingsViewController alloc] initWithNibName:@”SettingsViewController_iPad” bundle:nil] autorelease];
}

navController1 = [[[UINavigationController alloc] initWithRootViewController:viewController1] autorelease];
    navController2 = [[[UINavigationController alloc] initWithRootViewController:viewController2] autorelease];
    navController3 = [[[UINavigationController alloc] initWithRootViewController:viewController3] autorelease];
    
    // navigation bar color
    navController1.navigationBar.tintColor = [UIColor blackColor];
    navController2.navigationBar.tintColor = [UIColor blackColor];
    navController3.navigationBar.tintColor = [UIColor blackColor];

self.tabBarController = [[[UITabBarController alloc] init] autorelease];
self.tabBarController.viewControllers = @[navController1, navController2, navController3];
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];
return YES;
}

Any problems, please feel free to send me an email.

How to do a CSS Drop Shadow, you a web page.

Here is a page explaining how to create a drop shadow:

http://phoenity.com/newtedge/drop_shadow/

Creating a File System on an external drive.

mkfs.ext3 -j /dev/sdb1

Got sdb1 from fdisk -l or dmesg (from when the disk is enumerated)

(This probably wipes the disk)

Then you can mount it

mount -t ext3 /dev/sdb1 /mnt/usb-backup (make sure usb-backup exists)

I carried out the above when I was trying to mount an external hard disk and getting the following error:

mount: wrong fs type, bad option, bad superblock on ext3 partition….

Creating a Samba Folder

In the file:

$ sudo vi /etc/samba/smb.conf

Add the lines:
[folder-name]
comment = Shared reference data (will not be backed up)
path = /home/john/sambafolder
writeable = yes
browseable = yes
valid users = john

$  sudo service smbd restart

If a file exists in Perl

 #!/usr/bin/perl -w $filename = '/path/to/your/file.doc'; if (-e $filename) { print "File Exists!"; } 

 Also get the file size:

 #!/usr/bin/perl -w $filename = '/path/to/your/file.doc'; $filesize = -s $filename; print $filesize;

Samba file share with a Windows Server

You may need to install smbfs:

sudo apt-get install smbfs 

I assume samba is already installed, if not:

sudo apt-get install samba 

Create directory to mount 

$mkdir -p /mnt/win

Mount windows server to the newly created directory$mount -t smbfs -o username=winntuser,password=mypassword //windowsserver/sharename /mnt/win

(Source) 

Next create the password file /etc/sambapasswords:cat > /etc/sambapasswords username = winntuserpassword = mypasswordmake sure that only root have access to itchown root:root /etc/sambapasswordschmod 600 /etc/sambapasswords 

Add an entry to your /etc/fstab: 

//windowserver/share /mnt/win smbfs

auto,gid=users,fmask=0664,dmask=0775,iocharset=iso8859-15, credentials=/etc/sambapasswords 0 0

Call Sudo from a Perl Script

use Sudo; my $password = '*****';my $su = Sudo->new( { sudo => '/usr/bin/su', username => "*****" , password => $password, program => "/tmp/test.sh" , program_args => '' } ); $result = $su->sudo_run();print "$result \n";if (exists($result->{error}) ){ &handle_error($result);}else{ printf "STDOUT: %s\n",$result->{stdout}; printf "STDERR: %s\n",$result->{stderr}; printf "return: %s\n",$result->{rc};}

Install a Perl Module

$sudo perl -MCPAN -e shell

cpan> install Sudo
cpan>  exit

It will ask you for a username and password, enter something you can remember.

For the Sudo Module, which is the module I was trying to install:

http://search.cpan.org/~landman/Sudo/lib/Sudo.pm#NAME

Returning a value from Perl Script

Howto set-up a crontab file

To edit crontab:

$crontab -e

16 18 * * * /home/user/backup_script.pl > /home/user/backup_script.log

Use ‘>’ to output standard output to a log file.

See below for the sterling explaination I found (thank you to corenominal.org):

(Source: http://corenominal.org/howto-setup-a-crontab-file/)

Creating a crontab file

crontab -e

crontab -l

Crontab syntax

* * * * * command to be executed- - - - -| | | | || | | | +----- day of week (0 - 6) (Sunday=0)| | | +------- month (1 - 12)| | +--------- day of month (1 - 31)| +----------- hour (0 - 23)+------------- min (0 - 59)

Crontab examples

* * * * *  #Runs every minute30 * * * *  #Runs at 30 minutes past the hour45 6 * * *  #Runs at 6:45 am every day45 18 * * *  #Runs at 6:45 pm every day00 1 * * 0  #Runs at 1:00 am every Sunday00 1 * * 7  #Runs at 1:00 am every Sunday00 1 * * Sun  #Runs at 1:00 am every Sunday30 8 1 * *  #Runs at 8:30 am on the first day of every month00 0-23/2 02 07 *  #Runs every other hour on the 2nd of July

@reboot  #Runs at boot@yearly  #Runs once a year [0 0 1 1 *]@annually  #Runs once a year [0 0 1 1 *]@monthly  #Runs once a month [0 0 1 * *]@weekly  #Runs once a week [0 0 * * 0]@daily  #Runs once a day [0 0 * * *]@midnight  #Runs once a day [0 0 * * *]@hourly  #Runs once an hour [0 * * * *]

Multiple commands

@daily  && 

Disabling email notifications

>/dev/null 2>&1

Specifying a crontab file to use

crontab -u  

crontab -u tux ~/crontab

Removing a crontab file

crontab -r

Further information

man crontab

sudo: /etc/sudoers is mode 0640, should be 0440

Or

You can use the live ubuntu CD, and mount the hard disk’s file system, then do the following:

$ chmod 0440 /etc/sudoers

Reboot normally

Working out disk usage on Linux

If you are running our of space on a linux box, then the following command will tell you 20 largest folders:

du -a /home | sort -n -r | head -n 20


A report of the overall disk space, for all the connected hard disks:

df

Very useful!