In many iOS applications I have seen, the network activity indicator is either getting out of control or flickering displeasingly when something is being loaded from the network. The reason for the flickering is obviously a repeated and alternating call to

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
...
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
...
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

Well this is indeed the simplest way to trigger the activity indicator, but in order to avoid the flickering there should be a check whether another object still has network activity. In this case the activity indicator should not be hidden. Therefore you should write a helper class which has some kind of counter for the current network activities. E.g.

//Initialization
static NSUInteger counter = 0;
...
-(void)startNetworkActivityIndicator{
   ++counter;
   if(counter==1)
      [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
}
-(void)stopNetworkActivityIndicator{
   --counter;
   if(counter==0)
      [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}

The problem with this approach is that it’s difficult to ensure the counter becomes zero in any situation. You have to be very careful in case of failing network calls. Another problem is that an object which started the network activity indicator may be disposed for some reason. In that case the counter will never become zero again. This is bad. So why not keeping track of the objects which involve network activity instead of using a counter?
My solution uses a mutable set containing weak references to the objects which induce network activity. Thanks to ARC, should any of these objects be disposed, the weak reference becomes nil and is being removed from the set. This adjusts the object count used as condition for triggering automagically.

Here you go:

#import

@interface NetworkActivityIndicatorHelper : NSObject

+(NetworkActivityIndicatorHelper*)sharedHelper;
-(void)stopNetworkActivityForObject:(id)object;
-(void)startNetworkActivityForObject:(id)object;

@end

#import "NetworkActivityIndicatorHelper.h"

static NetworkActivityIndicatorHelper* sharedHelper;

@implementation NetworkActivityIndicatorHelper
{
    NSMutableSet* networkActivities;
}

- (id)init {
    self = [super init];
    if (self) {
        networkActivities = [NSMutableSet set];
    }
    return self;
}

+(NetworkActivityIndicatorHelper*)sharedHelper
{
    if (sharedHelper==nil) {
        sharedHelper = [[NetworkActivityIndicatorHelper alloc] init];
    }
    return sharedHelper;
}

-(void)checkIfShouldDisplayNetworkActivity
{
    for (id object in networkActivities.allObjects) {
        if(object != nil){
            [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
            return;
        }
    }
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}

-(void)stopNetworkActivityForObject:(id)object
{
    [networkActivities removeObject:object];
    [self checkIfShouldDisplayNetworkActivity];
}

-(void)startNetworkActivityForObject:(id)object
{
    __weak id objectRef = object;
    [networkActivities addObject:objectRef];
    [self checkIfShouldDisplayNetworkActivity];
}

@end

Note for english-speaking readers: Since I already had created this tutorial for a school project, this article is written in German. If you would like me to translate it to English, just drop me a line or give Google Translate a shot.

Mac Ports Installation

sudo port install ...

SSH Setup

Abbildung 1: Aktivierung von SSH in den Systemeinstellungen

Git

“Es gibt keine spezielle Version von Git für den Server (oder den Client), da jeder pull aus einem Repository das komplette Repository dupliziert, kann jedes Team-Mitglieder einen Server bereit stellen.”[1]

Authentifizierung

“Im folgenden wird die Authentifizierung über SSH beschrieben: Alle Teammitglieder werden auf ein bzw. mehrere Repositories mit Schreibrechten Zugriff haben, alle anderen haben keinen Zugriff.

Installation

#Auf dem Server
mkdir -p /Users/Shared/Git/Home
sudo dscl . create /Users/git
sudo dscl . create /Users/git PrimaryGroupID 1
sudo dscl . create /Users/git UniqueID 301
sudo dscl . create /Users/git UserShell /bin/bash
sudo dscl . passwd /Users/git $PASSWORD
sudo dscl . create /Users/git home /Users/Shared/Git/Home/

#Auf dem Server
sudo port install git-core python27

#Auf einem Client
scp ~/.ssh/id_rsa.pub mein-server.ch:/tmp/benutzername.pub

#Auf dem Server
cd /tmp
git clone git://eagain.net/gitosis.git
cd gitosis
sudo python setup.py install

#Auf dem Server
sudo mkdir /Volumes/PartitionName/repositories
sudo ln -s /Volumes/PartitionName/repositories /Users/Shared/Git/Home/repositories
sudo chown git /Volumes/PartitionName/repositories
sudo chown git /Users/Shared/Git/Home/repositories

#Auf dem Server
sudo su git
echo "PATH=/opt/local/bin:/usr/local/bin:$PATH" > ~/.bashrc
chown git ~/.bashrc

#Auf dem Server
sudo -H -u git gitosis-init < /tmp/benutzername.pub
sudo chmod +x /srv/git/repositories/gitosis-admin.git/hooks/post-update # muss ausführbar sein!

Initialized empty Git repository in ./
Initialized empty Git repository in ./

#Auf dem Client
Host mein-git-server.ch
  User git
  # falls man einen anderen Port verwendet, muss dieser hier gesetzt werden
  # Port 22
  IdentityFile ~/.ssh/id_rsa

cd /www # in das Verzeichnis wechseln, in dem man das Repository führen will
git clone git@mein-git-server.ch:gitosis-admin.git

Testen des SSH Zugangs

Verwaltung der Git Repositories

# ls -1 keydir/
alex.pub
andi.pub
claudi.pub
flobruit.pub
reinhard.pub

Neues Repository anlegen

mkdir mein_projekt
cd mein_projekt
git init
touch dummy.txt && git add dummy.txt && git commit -m 'Initial commit with dummy file'
git remote add origin git@mein-git-server.ch:mein_projekt.git
git push origin master:refs/heads/master

Repository entfernen

Neues Team-Mitglied aufnehmen

Team-Mitglied entfernen

Jenkins Installation

Standard Installation

sudo dscl . create /Users/jenkins
#Jenkins wird der Gruppe wheel hinzugefügt
sudo dscl . create /Users/jenkins PrimaryGroupID 0
sudo dscl . create /Users/jenkins UniqueID 300
sudo dscl . create /Users/jenkins UserShell /bin/bash
sudo dscl . passwd /Users/jenkins $PASSWORD
sudo dscl . create /Users/jenkins home /Users/Shared/Jenkins/Home/
mkdir -p /User/Shared/Jenkins/Home
chown -R jenkins: /Users/Shared/Jenkins/Home

<plist version="1.0">
<dict>
	<key>EnvironmentVariables</key>
	<dict>
		<key>JENKINS_HOME</key>
		<string>/Users/Shared/Jenkins/Home</string>
	</dict>
	<key>GroupName</key>
	<string>wheel</string>
	<key>KeepAlive</key>
	<true/>
	<key>Label</key>
	<string>org.jenkins-ci</string>
	<key>ProgramArguments</key>
	<array>
                <string>/bin/bash</string>
		<string>/Library/Application Support/Jenkins/jenkins-runner.sh</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
	<key>UserName</key>
	<string>jenkins</string>
</dict>
</plist>

#Auf dem Server
sudo su jenkins
ssh-keygen
#Standard Verzeichnis verwenden, leerer Passphrase verwenden
cat ~/.ssh/id_rsa.pub

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8n6utRXYaKMa4SOBYsc jVx1TPFgxMS77HjkUfJWz5bbch3CPRvUOqpQQyxj5dUedZe/cw7WU305 OyAmR7klXAebJRfDph+CPGkGOjmNsDZXQ/e0OC1RzcPb8C9nl jenkins@macbookpro

[gitosis]

[group gitosis-admin]
members = admin@lightforce.local admin@macbookpro jenkins@macbookpro
writable = gitosis-admin documentation graphics server TravelMate

#Auf dem Server
sudo su jenkins
mkdir /tmp/gittest
cd /tmp/gittest
git clone git@mein-git-server.ch:mein-repo.git

Abbildung 2: Anmeldung als jenkins Benutzer auf dem OS X Server

Build Jobs

API Documentation

rm -rf /Users/Shared/WebserverData/TravelMate/API-Documentation/*
/usr/local/bin/appledoc -p TravelMate -c "My Name" –create-html –no-create-docset –logformat 1 –verbose 3 –exit-threshold 2 -o /Users/Shared/WebserverData/TravelMate/API-Documentation $WORKSPACE/TravelMate

iPhone Applikation

Abbildung 3: Jenkins Webinterface mit konfigurierten Build Jobs

Zertifikate

security unlock-keychain -p <passwort>
#oder ohne ein Passwort zu verwenden
security unlock-keychain -u

Abbildung 4: Schlüsselbundverwaltung mit Entwicklerzertifikaten

Abbildung 5: Xcode Organizer mit installierten Provisioning Profiles

Build Job

<settings>
  <plugingroups>
    <plugingroup>org.jvnet.hudson.tools</plugingroup>
  </plugingroups>
</settings>

# Clone the repository
$ git clone git://github.com/rayh/xcode-hudson-plugin.git

# Go into the cloned repository
$ cd xcode-hudson-plugin

# Build the project
$ mvn install

Deployment zu TestFlightApp

curl http://testflightapp.com/api/builds.json
-F file=@$WORKSPACE/build/Release-iphoneos/TravelMate-Release-${JOB_NAME}-\"${BUILD_NUMBER}\".ipa
-F api_token='e1619135...'
-F team_token='52aca8b...'
-F notes='This is an autodeploy build from Jenkins!'
-F distribution_lists='Internal'

{
    "bundle_version": "1.0 (\"13\")",
    "install_url": "https://testflightapp.com/install/0c01fa526108f4691004383cd446d455-NDE1Mzgy/",
    "config_url": "https://testflightapp.com/dashboard/builds/complete/415382/",
    "created_at": "2011-09-27 09:32:07",
    "device_family": "iPhone",
    "notify": false,
    "team": "TravelMate",
    "minimum_os_version": "5.0",
    "release_notes": "This is an autodeploy build from Jenkins!",
    "binary_size": 32634
}Finished: SUCCESS

Abbildung 6: TestFlightApp Portal mit Dashboard der aktuellen Builds

Build Job für den App-Store Release

Abbildung 7: Build Konfiguration anlegen in Xcode

source="$WORKSPACE/build/Release-iphoneos/*.ipa"
target="/Users/Shared/WebserverData/TravelMate/$JOB_NAME"
rm -rf $target
mkdir $target
cp -R $source $target

Logic & Application Tests

Warning ${LINENO} "Skipping tests; the iPhoneSimulator platform does not currently support application-hosted tests (TEST_HOST set)."

export OTHER_TEST_FLAGS="-RegisterForSystemEvents"
RunTestsForApplication "${TEST_HOST}" "${TEST_BUNDLE_PATH}"

-(BOOL)isApplicationDirectoryCorrect:(NSString*)directory{
    NSRegularExpression* regex = [[NSRegularExpression alloc] initWithPattern:@"/[0-9A-F]+-[0-9A-F]+-[0-9A-F]+-[0-9A-F]+-[0-9A-F]+/" options:0 error:nil];
    NSUInteger numberOfMatches = [regex numberOfMatchesInString:directory options:0 range:NSMakeRange(0, [directory length])];
    return numberOfMatches>=1;
}

/**
 Returns the URL to the application's Documents directory.
 */
- (NSURL *)applicationDocumentsDirectory
{
    /*Fix to make application tests working in headless (command line) mode
     The problem is that in headless mode the Document directory (for core data) is not set correctly:
     ~/Library/Application Support/iPhone Simulator/Documents   instead of
     ~/Library/Application Support/iPhone Simulator/5.0/Applications/E1941BAA-8C4D-4AD4-8381-F1D128A1C05E/Documents/
     */
    //See http://www.gorillalogic.com/forumpost/1393
    //See http://denizdemir.com/2011/03/24/ios-unit-testing-with-xcode-4-and-core-data/
    if(![self isApplicationDirectoryCorrect:[[NSBundle mainBundle] description]])
        return [NSURL fileURLWithPath:[[NSFileManager defaultManager] currentDirectoryPath]];

    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

Code Coverage

Abbildung 8: Build Settings für Libprofile Konfiguration

python $WORKSPACE/Automation/gcovr.py -x -o $WORKSPACE/coverage.xml -r $WORKSPACE -e ".*/ThirdParty/.*" -e ".*/TravelMateTests/.*"

Automatischer Build-Start nach einem Commit

#!/bin/sh
USER=hudson
PASS=password

HUDSON_URL=http://$USER:$PASS@<my-build-server>:8080
JOB=$1
TOKEN=$2
CAUSE=$2

set -x
lwp-request -ds "$HUDSON_URL/job/$JOB/build?token=$TOKEN"

Webserver Installation

Konfiguration des Virtual Hosts

Abbildung 9: Konfiguration eines Virtual Hosts

Da das Directory Listing standardmässig deaktiviert ist, muss dieses in der Konfiguration noch aktiviert werden. Um möglichst flexibel zu bleiben, wird das Listing erst in der .htaccess Datei des entsprechenden Verzeichnisses aktiviert. Es muss jedoch für den virtuellen Host das Überschreiben dieser Einstellung erlaubt werden. Zu diesem Zweck muss die Konfigurationsdatei bearbeitet werden, welche für den neu erstellten virtuellen Host erzeugt wurde:

sudo nano /etc/apache2/sites/0000_192.168.0.5_80_my-host.com.conf

<VirtualHost 192.168.0.5:80>
        ServerName my-host.com
        ServerAdmin admin@example.com
        DocumentRoot "/Users/admin/WebserverData"
        DirectoryIndex index.html index.php /wiki/ default.html
        CustomLog "/var/log/apache2/access_log" combinedvhost
        ErrorLog "/var/log/apache2/error_log"

        <IfModule mod_ssl.c>
                SSLEngine Off
                SSLCipherSuite "ALL:!aNULL:!ADH:!eNULL:!LOW:!EXP:RC4+RSA:+HIGH:+MEDIUM"
                SSLProtocol -ALL +SSLv3 +TLSv1
                SSLProxyEngine On
                SSLProxyProtocol -ALL +SSLv3 +TLSv1
        </IfModule>

        <Directory "/Users/admin/WebserverData">
                Options All +MultiViews -ExecCGI -Indexes
                AllowOverride All
                <IfModule mod_dav.c>
                        DAV Off
                </IfModule>
        </Directory>

</VirtualHost>

sudo serveradmin command web:command=restoreFactorySettings

Basic Authentication

Options +Indexes
IndexOptions +FancyIndexing

AuthType Basic
AuthName "Protected directory"
AuthUserFile $PATH_TO_PWD_FILE
Require valid-user

Digest Authentication

htdigest -c ~/digest Private lightforce

Options +Indexes
IndexOptions +FancyIndexing

AuthType Digest
AuthName "Private"
AuthDigestFile ~/digest
Require user lightforce

Abbildung 10: Authentisierungsdialog im Browser

Abbildung 11: Directory Listing

Referenzen

If you have a first generation Apple TV you may also have installed ATV Flash. ATV Flash gives you SSH access to you Apple TV. The problem is, that the system user is «frontrow» and the according password is also «frontrow». So everyone who knows you IP address could log into your Apple TV with these insecure credentials and do some nasty stuff there. So what to do? You can either change the password or change the SSH authentication mode. The first option is really not recommended, since system services rely on these predefined credentials. Don’t criticise Apple for this issue, the system is designed as an isolated single user system, so this seems legit. So the way to go is to use public key infrastructure. And this is how you do it:

1. You will need a pair of private/public keys for your current user on your local machine. Use ssh-keygen to let the system create them for you. It will create the two files id_rsa id_rsa.pub in the directory ~/.ssh. The latter file contains your public key.
2. Now we want to add this public key to the servers authorized keys. Thus type cat ~/.ssh/id_rsa.pub and copy the output to your clipboard. Log into your Apple TV with ssh frontrow@appletv.local with the passwort frontrow. Then type nano ~/.ssh/authorized_keys to edit the file containing the authorized keys. There you can past your public key from the clipboard and save the file using ctrl + x.
3. Then we want to disable password authentication of the ssh server and make it use PKI instead.  Then you have to make the disk writeable using sudo mount -uw /dev/disk0s3. Type sudo nano /System/Library/LaunchDaemons/com.aTVFlash.dropbear.plist to edit the configuration file of the SSH server. Make the file look like the following:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>com.aTVFlash.dropbear</string>
	<key>OnDemand</key>
	<false/>
	<key>ProgramArguments</key>
	<array>
		<string>/usr/libexec/dropbear-keygen-wrapper</string>
		<string>-s</string>
		<string>-p</string>
		<string>22</string>
		<string>-b</string>
		<string>/Users/frontrow/.dropbear_banner</string>
	</array>
</dict>
</plist>

Now we are almost done. Type reboot to restart the server. Now you should be able to login to your Apple TV just by typing ssh frontrow@appletv.local! Now you can access your Apple TV from anywhere without having to worry about someone compromising your Apple TV by logging in with the default credentials.

References:

http://anthonyvance.com/blog/security/disable_ssh_passwords/

http://www.kilrathy.net/sites/ssh-public-key-authentication-und-osx.html

http://wl500g.info/showthread.php?t=24177

Man page scrolling

If you are a big fan of command line tools like me, you will often find yourself skimming large man pages. Unfortunately navigating within a man page is quite cumbersome when using the arrow keys to scroll up and down because they scroll only one line at a time. Since neither the arrow keys nor the “page up” and “page down” keys work as expected you will have to use the following command on a notebook keyboard:

Fn + shift + arrow (up/down)

If you have a full-size keybord you can similarly use:

Shift + page up/down

Navigating within text line

Beside scrolling vertically you certainly want to navigate within a text line. If you want to jump to the beginning/end of the line you need to press:

Ctrl + A /Ctrl + E

In order to navigate between words on one particular text line you have to use the following shortcuts:

Esc + F / Esc + B

You will notice that you cannot keep the esc key pressed down and continuously navigate by repeating F respectively B. Instead you need to re-press the escape key every time. In order to avoid this and also for a more convenient access we alter the terminal configuration as follows:

1. Open Terminal settings
2. Navigate to the «settings» tab
3. Navigate to the «keyboard» tab
4. Click «add»
5. Select left arrow as key and option key as the special key
6. Insert \033b as the text which should be sent to shell and confirm
7. Click «add»
8. Select right arrow as key and option key as the special key
9. Insert \033f as the text which should be sent to shell and confirm

In the following screenshot you see the preference windows with the selected «keyboard» tab:

The shortcut configurations should look like the following screenshots (the screenshots are in german, but you get the idea):

This solution has originally been found here: http://snipplr.com/view/28113/config-terminal-to-move-wordbyword/

Clear screen

Last but not least you can use the following command to clear the terminal’s screen:

Ctrl + L

Today I wanted to use the jQuery UI’s beautiful dialog box in order to display an iframe. After some googling I came across an article of Elijah Manor. He proposed a good solution. I modified his solution such that it would be possible to specify the width of the dialog box within the «a» tag. For that purpose you will need to set the «rev» attribute to a composed value of width and height.

For example: rev="300|400". This means that the dialog will have a width of 300 px and a height of 400 px. Additionally I added support for the «rel» attribute. This means that you simply can set the rel attribute to «dialog» and the href attribute to the desired URL and you will get a dialog with an iframe which loads the specified URL.

The following snippet shows a complete example of an «a» tag

<a title="Test dialog" rel="dialog" rev="675|465" href="http://www.google.ch">Dialog</a>

Place the following javascript somewhere in the header section. Make sure you have loaded jQuery and jQuery UI before executing this script.

$(function() {
	$('a[rel*=dialog]').click(function(e) {
		e.preventDefault();
		var $this = $(this);
		var horizontalPadding = 10;
		var verticalPadding = 10;
		var dialogWidth = ($this.attr('rev')) ? $this.attr('rev').split("|")[0] : 800;
		var dialogHeight = ($this.attr('rev')) ? $this.attr('rev').split("|")[1] : 600;

        $('<iframe src="' + this.href + '" />').dialog({
            title: ($this.attr('title')) ? $this.attr('title') : 'External Site',
            autoOpen: true,
            width: dialogWidth,
            height: dialogHeight,
            modal: true,
            resizable: false,
            autoResize: true,
        }).width(dialogWidth - horizontalPadding).height(dialogHeight - verticalPadding);
	});
});

Recently I came across the problem of performing an autostart of a HTML file on a CD. Unfortunately most of the scripts or executables found on the internet only perform an «open» command for the specified file. This launches the HTML file with the application which is associated with the .html file extension. On my test System the associated application was notepad++ which obviously wasn’t the desired behaviour. Instead I wanted the default browser to open and display the HTML file. Therefore I wrote my own C++  application which does that. Here is the result. You may freely use it.

#include <windows.h>
#include <string>
#include <iostream>
#include <sstream>
#include <shellapi.h>
#include <algorithm>

using namespace std;

string toLowerCase(string str){
	transform(str.begin(),str.end(),str.begin(),::tolower);
	return str;
}

string replace(const string &search, const string &replace, string haystack){
        string::size_type pos = haystack.find(search, 0);
		const int searchLength = search.length();
        while(pos != string::npos ){
                haystack.replace(pos, searchLength , replace);
                pos = haystack.find(search, pos+searchLength+1);
        }
        return haystack;
}

string getDefaultBrowserPath(){
	unsigned char temp[256] = {""};
	unsigned long size = sizeof(temp);
	HKEY hKey;

	RegOpenKey(HKEY_CLASSES_ROOT, "http\\shell\\open\\command", &hKey);
	RegQueryValueEx(hKey, NULL, NULL, NULL, temp, &size);
	RegCloseKey(hKey);
	stringstream ss;
	ss << temp;
	string path = ss.str();
	string needle(".exe");
	size_t found = toLowerCase(path).rfind(needle);
	path = path.substr(0,found+needle.size());//strip additional parameters for browser exe
	path = replace("\"","",path);//strip quotes
	return path;
}
string getExecutablePath(){
	TCHAR path[2048] = {0};
    GetModuleFileName( NULL, path, 2048 );
    const string exe_path(path);
	string file_path = exe_path.substr(0, exe_path.rfind("\\") + 1 );
	//PathRemoveFileSpec would also be nice
	return file_path;
}
int main(int argc, char **argv){
	string path;
	path = "\"" + getExecutablePath() + ((argc<2) ? "Start.html" : argv[1]) + "\"";
	//cout << getDefaultBrowserPath() << endl << path << endl;
	int result = (int) ShellExecute(NULL,"open",getDefaultBrowserPath().c_str(),path.c_str(),NULL,SW_SHOWNORMAL);
	if(result<=32){
		ShellExecute(NULL,"open",((argc<2) ? "Start.html" : argv[1]),NULL,NULL,SW_SHOWNORMAL);
	}
	return 0;
}

Have you ever asked yourself how you can lock your screen in OS X the same way you can do in Windows using CTRL + L ? It’s as easy as pie.
Open the keychain application under /Applications/Utilities/Keychain Access.app
Go to the application settings and make sure «Show status in menubar» is checked.

You will then see a lock icon in the status-icon part of the system menu bar. There you can click  «Lock screen». Enjoy.