Objective-C, display object info using %@ format

If needed to display the object info in an informative manner using %@ format, implement the "description" method, like so:

-(NSString *) description
{
   return [NSString stringWithFormat: @"%i/%i/%i", _month, _day, _year];
}

The idea is the same as, for example, overriding ToString() method in C#.

Create new object with some default parameters and NSMutable array to hold items

@interface Playlist : NSObject
@property (nonatomic, copy) NSString *playListName;
@property (nonatomic, strong) NSMutableArray *songs;

-(void)addSong:(Song *) aSong;
-(void)removeSong:(Song *)aSong;
-(id)initWithPlayListName:(NSString *)newPlayListName;
@end

//#import "Playlist.h"

@implementation Playlist
@synthesize playListName = _playListName, songs=_songs;

-(void)addSong:(Song *)aSong
{
    [_songs addObject:aSong];
}

-(void)removeSong:(Song *)aSong
{
    [_songs removeObject:aSong];
}

-(id)initWithPlayListName:(NSString *)newPlayListName
{
    self = [super init];
    if(self)
    {
        _playListName = newPlayListName;
        _songs = [NSMutableArray array];
    }
    
    return self;
}
@end

Objective-C tidbits

Sort an NSArray of NSIntegers:

NSArray *sorted = [arr sortedArrayUsingSelector:@selector(compare:)];

Iterate over items in NSCountedSet:

for(id i in set)
{
      NSLog(@"Item %@, count: %lu", i, (unsigned long)[set countForObject:i]);
}

Extract data from Excel into binary text file

In an Excel document (.xlsx, for .xls use

connStr

as the connection string), name one worksheet "Questions" and another "Answers" (no quotes in both cases). All columns are in Excel General format; the allowable format is noted in parentheses: Questions worksheet: QuestionID (Number), QuestionText (Text) Answers worksheet: AnswerID (Number), AnswerText (Text), QuestionID (Number), Correct (Text, but the only acceptable values are TRUE and FALSE).

var fileName = string.Format("{0}\\dbase.xlsx", Directory.GetCurrentDirectory());
var connStr = string.Format(
  "Provider=Microsoft.Jet.OLEDB.4.0; data source={0}; Extended Properties=Excel 8.0;", fileName);
var connectionString = string.Format(
  "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=Excel 12.0;", fileName);
var adapter1 = new OleDbDataAdapter("SELECT * FROM [Questions$]", connectionString);
var adapter2 = new OleDbDataAdapter("SELECT * FROM [Answers$]", connectionString);

var ds = new DataSet();

adapter1.Fill(ds, "Questions");
adapter2.Fill(ds, "Answers");

var answersTable = ds.Tables["Answers"].AsEnumerable();
var questionsTable = ds.Tables["Questions"].AsEnumerable();

List answers = answersTable.Where(
  x => x.Field("AnswerID") > 0.0).Select(x =>
     new TestQuestionAnswer
     {
         AnswerID = Convert.ToInt32(x.Field("AnswerID")),
         AnswerText = x.Field("AnswerText"),
         AnswerCorrect = x.Field("Correct"),
         QuestionID = Convert.ToInt32(x.Field("QuestionID"))
     }).ToList();

List questions = questionsTable.Where(
  x => x.Field("QuestionID") > 0.0).Select(x =>
    new TestQuestion
    {
        QuestionID = Convert.ToInt32(x.Field("QuestionID")),
        QuestionText = x.Field("QuestionText")
    }).ToList();


foreach (TestQuestion tq in questions)
{
    List a = answers.Where(x => x.QuestionID == tq.QuestionID).ToList();
    tq.Answers = a;
}

using (FileStream fs = new FileStream("data.dat", FileMode.Create))
{
    using (var writer = new BinaryWriter(fs))
    {
        writer.WriteList(questions);
    }
}
//fix for Syntax Highlighter plugin glitch:
//

Adjust the label text size of radiobutton or checkbox

txtQuestion.Text = "Question text";
int answerBreak = panel1.Height / NUMBEROFANSWERS;
int runningHeightTotal = 0;

panel1.Controls.Clear();

for (int i = 0; i < NUMBEROFANSWERS; i++)
{

  Font stringFont = new System.Drawing.Font(
    SystemFonts.DefaultFont.ToString(), 12, System.Drawing.FontStyle.Regular);

  //Gotcha 1: MeasureText does not produce accurate results
  Size textSize = TextRenderer.MeasureText(
    testQuestions[currentlyTestedQuestionID].Answers[i].AnswerText, stringFont);


  RadioButton rb = new RadioButton();
  rb.Tag = testQuestions[currentlyTestedQuestionID].Answers[i].AnswerID;

  //shift down if the previous answer took too much room
  rb.Location = new System.Drawing.Point(5, 
    (i * answerBreak >= runningHeightTotal ? i * answerBreak : runningHeightTotal + 5));
  rb.Text = testQuestions[currentlyTestedQuestionID].Answers[i].AnswerText;
  rb.Size = new System.Drawing.Size(textSize.Width, textSize.Height);
  rb.Font = stringFont;

  using (Graphics g = rb.CreateGraphics())
  {
    bool height = false;
    int linesNumber = 1;
    //so the text size is measured using the Graphics object
    Size s = g.MeasureString(rb.Text, rb.Font).ToSize();
    if (rb.Size.Height <= s.Height)
      height = true;

    if (s.Width > PANEL1WIDTH)
    {
      linesNumber = s.Width / 750;
      if (s.Width % PANEL1WIDTH > 0)
        linesNumber += 1;
    }

    rb.Size = new Size(PANEL1WIDTH, 
      height ? (s.Height + 5) * linesNumber : rb.Size.Height * linesNumber);
  }

  runningHeightTotal += rb.Height;

  panel1.Controls.Add(rb);
}

If checkbox's size needs to be adjusted, declare rb as a CheckBox, and everything will work just as well.

Get Stream for a BinaryReader for a file embedded in exe

public Stream GetDataFileStream(string resourceName)
  {
    foreach (string currentResource in System.Reflection.Assembly.
        GetExecutingAssembly().GetManifestResourceNames())
      if (currentResource.LastIndexOf(resourceName) != -1)
        {
          return System.Reflection.Assembly.GetExecutingAssembly().
            GetManifestResourceStream(currentResource);
        }

        throw new Exception("Resource not found : " + resourceName);
  }


//Then call this code:

using (BinaryReader reader = new BinaryReader(GetDataFileStream("data.dat")))
  {
    yourDataContainter = reader.ReadOrWhatever();
  }

In solution explorer, right-click on the text file that you want to embed, select "Properties". Under "Build Action", select "Embedded Resource", build solution.

How to extract embedded image/Как достать картинку из скомпилированного exe

Image _image;
List resourcenames = new List();//syntax highlighter glitch fix: 
resourcenames.AddRange(Assembly.GetExecutingAssembly().GetManifestResourceNames());
string resourcename = resourcenames.Find(
   delegate(string item) 
      { return item.EndsWith("template1.jpg"); });
Stream s = Assembly.GetExecutingAssembly().GetManifestResourceStream(resourcename);
BinaryReader br = new BinaryReader(s);

MemoryStream ms = new MemoryStream(br.ReadBytes((int)s.Length));
_image = Image.FromStream(ms);
br.Close();
s.Close();
br.Dispose();
s.Dispose();

In solution explorer, right-click on the text file that you want to embed, select "Properties". Under "Build Action", select "Embedded Resource", build solution.

How to extract embedded text file/Как достать текстовый файл, скомпилированный в exe

        public static string ExtractResource(string resourceName)
        {
            foreach (string currentResource in System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceNames())
                if (currentResource.LastIndexOf(resourceName) != -1)
                {
                    string fqnTempFile = System.IO.Path.GetTempFileName();
                    string path = System.IO.Path.GetDirectoryName(fqnTempFile);
                    string rootName = System.IO.Path.GetFileNameWithoutExtension(fqnTempFile);
                    string destFile = path + @"\" + rootName + "." +
                    System.IO.Path.GetExtension(currentResource);

                    System.IO.Stream fs = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream(currentResource);

                    byte[] buff = new byte[fs.Length];
                    fs.Read(buff, 0, (int)fs.Length);
                    fs.Close();

                    System.IO.FileStream destStream = new System.IO.FileStream(destFile,FileMode.Create);
                    destStream.Write(buff, 0, buff.Length);
                    destStream.Close();

                    return destFile;
                }

            throw new Exception("Resource not found : " + resourceName);

        }

In solution explorer, right-click on the text file that you want to embed, select "Properties". Under "Build Action", select "Embedded Resource", build solution.

How to set Google Chrome's search engine to Google US English by default

Instructions are taken from here: http://www.google.com/support/forum/p/Chrome/thread?tid=581638f51350589b&hl=en. 
1. Go to Wrench > Options (Preferences on Mac) > Basics > Search > Manage
2. Select Add ("+" sign on Mac)
3. For "Name" and "Keyword," type whatever
4. For "URL," enter http://www.google.com/search?q=%s
5. Click O.K. 6. Select your new search engine from the list and click "Make default"
7. Click "Close"

Generate random text in Microsoft Word

If you type in =rand(10,10) in Microsoft Word, it will generate 10 paragraphs of text with 10 sentences in each paragraph. Looks like the text is coming from Word help files, but it is a great feature.

How to make bootable USB flash drive with just Windows

diskpart
select disk 1
clean
create partition primary
select partition 1
active
format fs=fat32
assign
exit

xcopy d:\*.* /s/e/f e:\

From: http://www.techmixer.com/install-windows-vista-from-bootable-usb-flash-memory-drive/

Firefox 5 tab scrolling issue

I like seeing all my tabs at once in my browser, so here is how I did it in Firefox 5:

1. Open Firefox menu -> Help -> Troubleshooting information.
2. Click "Open Containing Folder" button.
3. Create "chrome" folder inside the folder that had just opened up after step 2.
4. Create a text file, call it "userChrome.css" and paste the following into it:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); 

.tabbrowser-tab {min-width: 016px !important;}
.tabbrowser-tab {clip-width: 016px !important;} 

Windows Phone 7: Iterate over ListBoxItems in a list box to focus on a control

I am developing a small Windows Phone 7 application and I ran into a wall. I am updating items within a ListBox and I need to set focus on a control after the update. It turns out that it is not a trivial task -- I need to iterate over the entire list box to get to the control and then set focus on it.

Here is the XAML of my list box:

I was using the VisualTreeHelper class to iterate over the ListBox, but I was not getting to the ListBoxItems. I was getting ListBox, ScrollViewer, Border, Grid, ContentPresenter, ItemsPresenter, VirtualizingStackPanel, and other controls, but no ListBoxItems. After reading this, the problem was fixed by calling the

UpdateLayout

method. The rest was simple. Here is my code.

void SetFocusOnTextBox(DependencyObject element, int primaryKey)
        {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(element); i++)
            {
                if (foundItem == false) //global flag that stops processing once the control is found
                {
                    DependencyObject child = VisualTreeHelper.GetChild(element, i);
                    StackPanel s = child as StackPanel;
                    if (s != null)
                        FindAllChildrenOfAStackPanel(child, primaryKey);
                    if (foundItem == false)
                        SetFocusOnTextBox(child, primaryKey);
                    else
                        break;
                }
            }
            foundItem = false;
        }

        void FindAllChildrenOfAStackPanel(DependencyObject element, int primaryKey)
        {
            StackPanel s = element as StackPanel;
            if (s != null)
            {
                for (int i = 0; i < VisualTreeHelper.GetChildrenCount(element); i++)
                {
                    TextBox t = VisualTreeHelper.GetChild(element, i) as TextBox;
                    if (t != null)
                        if (t.Name == primaryKey)
                        {
                            t.Focus();
                            foundItem = true;
                            break;
                        }
                }
            }
        }

Excel and multithreading

I was working on an application that opens an Excel spreadsheet, pulls some data out, manipulates it, and exports it into CSV. I ran into a couple of interesting things, they are worth mentioning.

All the computers that will run the code below need to have Microsoft Office and Microsoft Office PIA (Primary Interop Assemblies) installed. More info here: http://msdn.microsoft.com/en-us/library/15s06t57.aspx. Make sure to match the version of Microsoft Office and PIA components. Then, on the development machine, in the solution, add reference to Microsoft.Office.Interop.Excel dll, which, on my computer, was located at "C:\Program Files (x86)\Microsoft Visual Studio 10.0\Visual Studio Tools for Office\PIA\Office12\Microsoft.Office.Interop.Excel.dll".

My form looks like this:

The use of delegates make the application a bit more complicated, but it adds a nice option to display progress bars. I got the idea and some code here: http://msdn.microsoft.com/en-us/library/ms993020.aspx. The only thing I added is the call on line 69 for a method that would start as soon as the ProcessData method finishes working.

The other thing I changed was disabling the minimize/maximize/close buttons for the form (line 19). The reason for that is if the user quits application by clicking the close button in the top right corner, Excel process still stays in memory. If the user exits the application using the "Close" button that triggers the event on line 72, Excel process is properly disposed.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
using System.Threading;

namespace MultiThreadExcel
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.ControlBox = false;
        }

        private Excel.Application app = null;
        private Excel.Workbook workbook = null;
        private Excel.Worksheet worksheet = null;
        private Excel.Sheets sheets;
        string fileName = @"D:\test.xlsx";

        delegate void ProcessDataDelegate(int linesToRead);
        delegate void ShowProgressDelegate(string progressMessage, int totalDigits, int digitsSoFar);
        
        public void AddComplete(IAsyncResult itfAR)
        {
            if (workbook != null)
                workbook.Close(false, fileName, false);
            if (app != null)
                app.Quit();
        }

        private void ProcessData(int linesToRead)
        {
            app = new Excel.Application();
            workbook = app.Workbooks.Open(fileName, 0, false, 5, "", "", false, Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false);
            sheets = workbook.Worksheets;
            worksheet = (Excel.Worksheet)sheets.get_Item(1);
            for (int i = 0; i < linesToRead; i++)
            {
                ShowProgress("Processing...", linesToRead, (i+1));
                Thread.Sleep(50);
            }
        }

        void ShowProgress(string progressMessage, int totalDigits, int digitsSoFar)
        {
            if (progressBar1.InvokeRequired == false)
            {
                progressBar1.Maximum = totalDigits;
                progressBar1.Value = digitsSoFar;
            }
            else
            {
                ShowProgressDelegate showProgress = new ShowProgressDelegate(ShowProgress);
                BeginInvoke(showProgress, new object[] { progressMessage, totalDigits, digitsSoFar });
            }
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            ProcessDataDelegate proDa = new ProcessDataDelegate(ProcessData);
            IAsyncResult iftAR = proDa.BeginInvoke(100, new AsyncCallback(AddComplete), null);
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
    }
}

Programming for MS Office -- side note

So one interesting thing I discovered while programming for MS Office. If the user's version of the office suite does not match yours, make sure you download and reference the correct Office dll. The Office dll's are called IPA, that stands for the "Primary Interop Assembly." Office 2010 PIA is not out yet.

Let's say you are programming for Office 2007. Download (google and get from microsoft.com) and install the Office 2007 PIA. You have to have the Office suite installed on that computer as well. Once installed, go into the project references and find the proper dll, and use it in the project. The client will also have to have the PIAs installed to get your project to work.

C# syntax test

Console.WriteLine("Hello World!");

Item loader

In order to fill the data into the ItemTester, I will write another application, ItemLoader. Here are the requrements:

The program, ItemLoader, is an application that helps create the database of question/answer pairs for ItemTester.

Functional Requirements.

The program will:

1. allow the user to enter question/answer pairs one-by-one (also requiring topic(s) for an item).

2. allow the user to process a batch file in a predefined format.

3. check the new words against the database to make sure this question/answer pair does not already exist.


The format for the batch file:

Question///Answer///tag1;tag2;tag3

3. write out the user's input into the XML file.

A new app

I decided to write an application to learn new foreign words. The app will be pretty simple -- it will offer you a word and four choices of what it can be, you have to choose the right answer. In order to do things right, I want to start with the Requirements Document. This will be my contract and I will stick to it.

Functional Requirements

The application must help the user train to learn new words. The interface should offer the user a question and four possible answers. The user must choose one of the four answers, if he/she gets it right, the application updates the number-correct field. Once the user is consistently right, the word is shown less and less.

The application will:
1. read the question/answer pairs from storage, load them into the memory.

2. distinguish the question/answer pairs by topics. A question/answer pair may belong to multiple topics.

3. offer the user the choice of topics. A user can choose one or more topics to practice.

4. keep track of the percentage of the correct answers, incrementing/decrementing on each answer on the word.

5. ask user what is the threshold after which he/she does not want to see the word anymore.

6. offer a "refresher" mode for those words whose number-correct ratio is above the threshold.

7. offer the user a choice of four answers, one of which is correct, and the other three are the answers for items belonging to the same topic.

8. shuffle the positions of the possible answers. If the topic has less than 4 items total, the application must select other wrong answers from any other topics.



Database requirements:

XML file will suffice.

Other requirements:

The program must be initially implemented in Windows forms using LINQ. The program's functionality must be abstracted such that it is easy to migrate it to an ASP.Net application.

The program will be written in .Net, C#.

The program must be easy to use.

My resolutions for 2010

1. Program one substantial application using a functional language
2. Read 10 programming books:
- Real World Haskell
- Functional programming tutorial
- Pragmatic programmer
- Code Complete
- Microsoft TDD book
- Structure and Interpretation of computer programs
- Review Joe Celko's SQL for Smarties
- Read Joe Celko's SQL Puzzles & Answers
+ others (at least two).
3. Learn basic Japanese
4. Enrich my cooking skills
5. Work out at least 2 times a week
6. Find an interesting job

How to edit a GridView items inside a repeater?

You know, the usual:

<asp:Repeater ...
<itemtemplate>
<asp:gridview id="gv1" runat="server">
</itemtemplate>
</asp:Repeater>

When I was working on my app, I had a long gridview of multiple records per day, multiple days, all one list. When it was 10 records, it was ok. But as I started adding data, it started looking long and boring. I decided to group it by day, and it looked nice until I had to edit individual records. I did not change any event declarations from before, my methods had the same names, and they seem to be working, but none of the gridviews would change their edititemindexes. I checked out a couple of posts and people had the same issues, they assign events, they get executed, but gridviews would not react in any way.

The problem is happening because every time I'd call .DataBind method on the Repeater (then calling the .DataBind method on individual gridviews in the repeater's ItemDataBound event), the entire Repeater would get rebuilt and the EditItemIndex property on that particular gridview would not matter anymore because the server would not know which gridview needed to be edited.

The trick was relatively easy. Instead of rebinding the entire repeater, only that particular gridview needed to be re-databound. I figured out a way to pull just those particular day's records and my GridView_RowEditing event looks like:

protected void GridView1_RowEditing(object sender, GridViewEventArgs e)
{
GridView gv1 = (GridView)sender;
if(gv1 != null)
{
gv1.EditIndex = e.NewEditIndex;
gv1.DataSource = myDataSource;
gv1.DataBind();
}
}

Instead of binding the entire Repeater and losing all valuable information, I just bound that particular gridview by casting the sender object as a GridView. RowCancelingEvent and RowUpdatingEvent -- same thing. Cast the sender object and work with it as much as you need.