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Category: Code

Undefined symbols: _SCNetworkReachabilityCreateWithName

I was recently adding some code to check for the availability of the network, so I can display an error to the user if unavailable.

I looked at the SeismicXML application and borrowed the following code:

// Use the SystemConfiguration framework to determine if the host that provides
// the RSS feed is available.
- (BOOL)isDataSourceAvailable
    static BOOL checkNetwork = YES;
    if (checkNetwork) { 
// Since checking the reachability of a host can be expensive, 
// cache the result and perform the reachability check once.
        checkNetwork = NO;
        Boolean success;    
        const char *host_name = "";
		//const char *host_name = "localhost";

        SCNetworkReachabilityRef reachability =
SCNetworkReachabilityCreateWithName(NULL, host_name);
        SCNetworkReachabilityFlags flags;
        success = SCNetworkReachabilityGetFlags(reachability, &flags);
        _isDataSourceAvailable = success && 
(flags & kSCNetworkFlagsReachable) && 
!(flags & kSCNetworkFlagsConnectionRequired);
    return _isDataSourceAvailable;

I wouldn’t compile unless I added the following import:

#import <SystemConfiguration/SystemConfiguration.h> 

After adding this I still go 2 more errors, but these were a bit more cryptic.

 Undefined symbols:
"_SCNetworkReachabilityCreateWithName", referenced from:
-[TheElementsAppDelegate isDataSourceAvailable] in TheElementsAppDelegate.o
"_SCNetworkReachabilityGetFlags", referenced from:
-[TheElementsAppDelegate isDataSourceAvailable] in TheElementsAppDelegate.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

After some digging around I realized that I was missing the SystemConfiguration.framework framework.

So here is what I did to add it.
1. I right click on “Frameworks” and choose: Add < Existing Framework

2. Browsed to the file: /System/Library/Frameworks/SystemConfiguration.framework

3. Rebuilt the project and my error was gone.


Distribution Provisioning Profile not showing up

I recently spent about 2 hours trying to get my Distribution Provisioning Profile to show up. I followed the instructions and did everything, but still it would not show up.

Then I came across this thread:

The first suggestion was to create a new project. I created a new project and my Distribution Provisioning profile appeared in it. Then I went back to my main project and it appeared there too. Problem solved!

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Adobe Flex ComboBox Cell Padding

Recently I was trying to figure out how to make the padding in the cells of a <mx:comboBox> smaller than the default. This proved to be much harder than I thought. But I eventually found a solution.

Here is what the default looks like:

Here is the code I came up with:

<mx:Script xmlns:mx="">
import mx.controls.Alert;
import mx.core.Application;
public var app:* = Application( Application.application );
private function comboBox_open(evt:DropdownEvent):void {
evt.currentTarget.dropdown.variableRowHeight = true;
<mx:ComboBox id=”myComboBox” dataProvider=”{mx.core.Application.application.bbapp.cityXML}” labelField=”NAME”
close=”app.closeHandler(event)” cornerRadius=”0? dropdownStyleName=”gameSelectBox” visible=”false” fontSize=”12? open=”comboBox_open(event);”>
<mx:Label text=”{data.NAME}” paddingTop=”-5? paddingBottom=”-5?/>

And here is the final output:


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Open Link in Safari

Here some sample code showing you how to open a link in Safari when clicked on in your UIWebView. The method shouldStartLoadWithRequest is a delegate method that is called when a link is clicked on. You can override the method and tell it to open in Safari.

- (BOOL)webView:(UIWebView *)webView 
     shouldStartLoadWithRequest:(NSURLRequest *)request
     navigationType:(UIWebViewNavigationType)navigationType; {

    NSURL *requestURL = [ [ request URL ] retain ]; 
    // Check to see what protocol/scheme the requested URL is.
    if ( ( [ [ requestURL scheme ] isEqualToString: @"http" ] 
    	|| [ [ requestURL scheme ] isEqualToString: @"https" ] ) 
    	&& ( navigationType == UIWebViewNavigationTypeLinkClicked ) ) {
        return ![ [ UIApplication sharedApplication ] openURL: [ requestURL autorelease ] ]; 
    // Auto release 
    [ requestURL release ];
    // If request url is something other than http or https it will open 
    // in UIWebView. You could also check for the other following 
    // protocols: tel, mailto and sms
    return YES;

PostgreSQL Sequences

Today I was trying to figure out the name of a sequence in the db, so I could add it to my hibernate mapping.  I usually use pgAdmin, but that wasn’t an option today.  After some searching, I eventually figured it out, but it took me awhile…

Get a list of all Sequences in a schema:

select sequence_name from information_schema.sequences where sequence_schema='public'

Get a list of all tables:

select table_name from information_schema.tables where table_schema='public'

Get the next sequence value for sequence: foo_seq

SELECT setval('foo_seq', 42);

Update the sequence to 42 for sequence: foo_seq

select nextval('foo_seq');

Note if you are looking for more info on sequences check here: Sequence-Manipulation Functions

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How To Rename an iPhone XCode Project

I recent created a new iPhone XCode project based off of one of the samples provided by Apple. Beause of this the XCode project was called AppleSample.xcodeproj and it built an app called I wanted to rename the project and give it my own name. It’s not as easy as it sounds. Here are some instructions which are based off some instructions I found here (

  • Copy/rename the folder into new name
  • Get inside the new folder and rename the .pch and .xcodeproj files. Example rename AppleSample.xcodeproj to MyCoolApp.xcodeproj — and — rename AppleSamplePrefix.pch to MyCoolApp_Prefix.pch
  • Delete the build folder. (Using the finder)
  • Open .xcodeproj file in text editor, like TextMate or TextWrangler. That’s actually a folder, which contains 4 files (you can also right-click and do Show package contents, which will reveal the files)
  • Open project.pbxproj in text editor and replace all instances of the old name with the new name. Be careful not to do a find an replace. Since the default name was AppleSample, there were several references to: AppleSampleAppDelegate.h and AppleSampleAppDelegate.m. You do not want to replace these unless you also rename that file.
  • Open .pbxuser where is your user name. Then repeat the previous step by renaming. I’m not sure if this is necessary. You may even be able to delete this file? But changing this file worked for me.
  • Load the project file in XCode, do Build/Clean all targets

After following these steps, I was able to open the project and build it to the simulator and the device.

I had one additional problem that I came across later that required a fix. When I finially built the application for “deployment” to the App Store, I had problems signing the code. I complained that it couldn’t find the Certificate for “Scott Anguish”. I looked in the build settings and couldn’t find reference to this name. So again I opened project.pbxproj inside of MyCoolApp.xcodeproj and found 2 instances of this line:

CODE_SIGN_IDENTITY = “Scott Anguish”;

I replaced both of them with the correct code signing identity and it worked!

UPDATE: Check out this bash script which does it for you automatically:


XCode 3 Debugger and Screenshots

I’ve been doing some iPhone development with XCode recently and had problems using the debugger on the device (not the simulator) and also with taking screenshots.

When installing an application on to the device, the debugger would say:

"Failed to start remote debugserver for"

I search around looking for a solution. In a thread somewhere, someone suggested reinstalling the SDK from scratch. I had first installed the SDK about a year ago when it came out. I then installed several updates over it. For whatever reason, that cause problems.

After reinstalling the latest SDK from Apple website, the debugger worked perfectly! And I was able to take screenshots from the device.

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Print Perl Path

I was having issues with one of my Perl programs and needed to look at the path. To do so, you can print your Perl path like:

perl -e "print qq(@INC)"

Or if you want to print your path of a running program to the log:

warn "path=" .  qq(@INC) . "nn"
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I’ve been wanting to play around with the Google App Engine and Yahoo! User Interface Library (YUI), so I created a simple app called WebStickies:

WebStickies is a place on the web to save your notes.  You can login using your Google Account and your stickies will be saved. 

I’ve got lots of feature in mind, but who know if I’ll have time to add them. Enjoy.

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