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So, I made an array of NSString objects that I wanted to lay out, around that circle.

NSArray* sections = [[NSArray alloc] initWithObjects:@"text1", @"text2", @"text3", @"text4", nil];

- (UIImage*) createMenuRingWithFrame:(CGRect)frame
{
    // First fix the frame to make sure it uses the right scaling (iPhone 4 / iPad compatibility).
	frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width * scale, frame.size.height * scale);

    // Same for the text radius
	float scaledTextRadius = textRadius * scale;
	float scaledRingWidth = ringWidth;

    // Define the centerpoint of the circle.
	CGPoint centerPoint = CGPointMake(frame.size.width / 2, frame.size.height / 2);

    // self.menuItemsFont is of the type UIFont, which I use to get the font for displaying the text on the circle.
	char* fontName = (char*)[self.menuItemsFont.fontName cStringUsingEncoding:NSASCIIStringEncoding];

    // 2 UIColor's, which I need for the color of the circle and for the text
	ringColor = [UIColor colorWithRed:1 green:1 blue:1 alpha:0.7];
	textColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:1];

	CGFloat* ringColorComponents = (float*)CGColorGetComponents(ringColor.CGColor);
	CGFloat* textColorComponents = (float*)CGColorGetComponents(textColor.CGColor);

	CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(NULL, frame.size.width, frame.size.height, 8, 4 * frame.size.width, colorSpace, kCGImageAlphaPremultipliedFirst);

	CGContextSetTextMatrix(context, CGAffineTransformIdentity);

	CGContextSelectFont(context, fontName, 18 * scale, kCGEncodingMacRoman);
	CGContextSetRGBStrokeColor(context, ringColorComponents[0], ringColorComponents[1], ringColorComponents[2], ringAlpha);
	CGContextSetLineWidth(context, scaledRingWidth);

	CGContextStrokeEllipseInRect(context, CGRectMake(scaledRingWidth, scaledRingWidth, frame.size.width - (scaledRingWidth * 2), frame.size.height - (scaledRingWidth * 2)));
	CGContextSetRGBFillColor(context, textColorComponents[0], textColorComponents[1], textColorComponents[2], textAlpha);

	CGContextSaveGState(context);
	CGContextTranslateCTM(context, centerPoint.x, centerPoint.y);

    // define the angles of the texts to divide them evenly on the circle.
	float angleStep = 2 * M_PI / [sections count];

    // I set the starting-angle on 90 degrees, to make sure the first text was ON TOP of the circle.
	float angle = degreesToRadians(90);

    // Some custom text-radius fixing (and scaling for iPhone 4 & iPad). To make sure my text centered nicely.
	scaledTextRadius = scaledTextRadius - 12 * scale;

    // Loop through texts and draw them at the appropriate angle.
	for (NSString* text in sections)
	{
        // call a method that actually draws the text at an angle
		[self drawStringAtContext:context string:text atAngle:angle withRadius:scaledTextRadius];
		angle -= angleStep;
	}

	CGContextRestoreGState(context);

	CGImageRef contextImage = CGBitmapContextCreateImage(context);

    // Release the stuff to avoid memory leaks.
	CGContextRelease(context);
	CGColorSpaceRelease(colorSpace);

    return [UIImage imageWithCGImage:contextImage];

}

// This method draws the text at an angle, while the location is based on the radius + angle.
- (void) drawStringAtContext:(CGContextRef) context string:(NSString*) text atAngle:(float) angle withRadius:(float) radius
{
	// Scale the fontsize to match UIScreen scaling
	UIFont* scaledMenuItemsFont = [menuItemsFont fontWithSize:18 * scale];

	// Get the size of the string when it would be drawn with the selected font
	CGSize textSize = [text sizeWithFont:scaledMenuItemsFont];

	float perimeter = 2 * M_PI * radius;

	// determine the angle of the text.
	float textAngle = (textSize.width) / perimeter * 2 * M_PI;
	angle += textAngle / 2;

	// We loop through each letter in the string, so we can set the angle for each letter right
	for (int index = 0; index < [text length]; index++)
	{
	    // Get the correct letter by the index
		NSRange range = {index, 1};
		NSString* letter = [text substringWithRange:range];
		char* c = (char*)[letter cStringUsingEncoding:NSASCIIStringEncoding];
		CGSize charSize = [letter sizeWithFont:scaledMenuItemsFont];

	    // Determin the X and Y position of the letter based on the angle and the radius
		float x = radius * cos(angle);
		float y = radius * sin(angle);

		float letterAngle = (charSize.width / perimeter * -2 * M_PI);

	    // Save the state of the context, because rotations are based on the original origin
		CGContextSaveGState(context);
		CGContextTranslateCTM(context, x, y);
	    // Rotate the canvas so we can just draw our text horizontally
		CGContextRotateCTM(context, (angle - 0.5 * M_PI));
		CGContextShowTextAtPoint(context, 0, 0, c, strlen(c));
	    // Restore the context again.
		CGContextRestoreGState(context);

		angle += letterAngle;
	}
}

I came to this solution after I asked a question on StackOverflow, which was helpfully demonstrated by Dribbel on how to do it. Credits for that to him.

Step 1: Adding the right delegates
Make sure your current class (probably a ViewController) uses the following delegates:

• UIActionSheetDelegate
• UINavigationControllerDelegate
• UIPickerViewDelegate
• UIPickerViewDataSource

Step 2: Trigger the UIActionSheet
Go to the method where you want to make the UIPickerView appear. In my case it is when I select a row from a table, but of course it could also be when you push a button or anything you want.

/* first create a UIActionSheet, where you define a title, delegate and a button to close the sheet again */
UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Select position" delegate:self cancelButtonTitle:@"Done" destructiveButtonTitle:nil otherButtonTitles:nil];
/* I always give my controls a tag, to make sure I can work with multiple actionsheets in one View (to identify them when an event triggers */
actionSheet.tag = POSITION_ROW;
actionSheet.actionSheetStyle = UIActionSheetStyleDefault;

/* Initialize a UIPickerView with 100px space above it, for the button of the UIActionSheet. */
UIPickerView* positionPicker = [[UIPickerView alloc] initWithFrame:CGRectMake(0,100, 320, 216)];
positionPicker.dataSource = self;
positionPicker.delegate = self;

/* another unique tag for this UIPicker */
positionPicker.tag = POSITION_ROW;

/* Add the UIPickerView to the UIActionSheet */
[actionSheet addSubview:positionPicker];

/* Select the previous selected value, which for me is stored in 'currentPosition' */
[positionPicker selectRow:currentPosition inComponent:0 animated:NO];

/* clean up */
[positionPicker release];

/* Add the UIActionSheet to the view */
[actionSheet showInView:self.view];

/* Make sure the UIActionSheet is big enough to fit your UIPickerView and it's buttons */
[actionSheet setBounds:CGRectMake(0,0, 320, 411)];

/* clean up */
[actionSheet release];

Step 3: Implementing the datasource and delegates for the UIPickerView
Now, the triggering of the UIActionSheet is now working, but you would also like to have some items in your UIPickerView. Well, take a look at the following code and read the comments.

/* Defines the total number of Components (like groups in a UITableView) in a UIPickerView */
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;
{
    return 1;
}

/* What to do when a row from a UIPickerView is selected. This will trigger each time you scroll the UIPickerView, so only lightweight stuff. */
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
	overlayPosition = row;
	[tableSettings reloadData];
}

/* For me the number of items in the UIPickerView is known on compile time. So here I just return 3 */
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;
{
    return 3;
}

/* Because the UIPickerView expects a UIView for every row you insert in the UIPickerView, you need to make one. What I do here is really simple. I create a UILabel* and with each row it requests I just change the text in the UILabel. */
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
/* Create a UILabel and set it 40 pixels to the right, to make sure it is put nicely in the UIPickerView */
	UILabel *label = [[[UILabel alloc] initWithFrame:CGRectMake(40, 0, 280, 25)] autorelease];
	label.textColor = [UIColor blackColor];
	label.backgroundColor = [UIColor clearColor];

	switch (row)
	{
		default:
		case kUnderClock:
			label.text = @"Under clock";
			break;
		case kAboveSlider:
			label.text = @"Above lock slider";
			break;
		case kCenter:
			label.text = @"Vertically centered";
			break;
	}

	return label;
}

Step 4: Do stuff when buttons on the UIActionSheet are clicked
Now, the final thing you have to do is make sure you listen to the events of the UIActionSheet also. So here is the code:

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
	if (actionSheet.tag == POSITION_ROW)
	{
/* Do stuff here, only intended for the right UIActionSheet. This only applies for when you use multiple UIActionSheets on the same ViewController. Closing it is unnecessary, because you already specified a destructive button. */
	}
}

So after a coupe of google searches, I came up with the following solution, follow these steps and you will be sending emails with attachments before you can say “emails with attachments” 250 times.

Step 1
First add the MessageUI framework in your application.

Step 2
The class you want to use the functionality in, should get the following 2 imports:

#import
#import 

Step 3
Make sure your class listens to the MFMailComposeViewControllerDelegate.

Step 4
Next up, is to add code to add an attachment to the mail composer and open it up.

MFMailComposeViewController* composer = [[MFMailComposeViewController alloc] init];
composer.mailComposeDelegate = self;

[composer setSubject:@"The subject of the email"];
NSData *imageData = UIImagePNGRepresentation([UIImage imageNamed:@"test.png"], 1);
[composer addAttachmentData:imageData mimeType:@"image/png" fileName:@"test.png"];
NSString *emailBody = @"Check out this amazing PNG!";
[composer setMessageBody:emailBody isHTML:YES];
[self presentModalViewController:composer animated:YES];
[composer release];

Step 5
Add this method, to make sure you get back full control over your view-controller:

- (void) mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error
{
	[self dismissModalViewControllerAnimated:YES];
}

In this last method you can also perform error checking, which is not included in this example. Hope this helps anyone, and if not… too bad

For example, sometimes you receive a string like this: Terminator_2$003A_Judgment_Day. I wanted to convert the weird encoding they use, so I wrote a piece of code for that. It might be that this could be encoded some other way and then I would like to hear from you, but here is my code:

+ (NSString*) replaceHexInString:(NSString*) value
{
	NSRange range = [value rangeOfString:@"$00"];

	while (range.location != NSNotFound)
	{
		if (range.location + 5 <= [value length])
		{
			NSString* hexValue = [value substringFromIndex:range.location];
			hexValue = [hexValue substringToIndex:5];
			NSString* newHexValue = [hexValue stringByReplacingOccurrencesOfString:@"$" withString:@"0x"];

			unsigned int dec;
			NSScanner *scan = [NSScanner scannerWithString:newHexValue];

			if ([scan scanHexInt:&dec])
			{
				NSString* convertedValue = [NSString stringWithFormat:@"%c", dec];
				value = [value stringByReplacingOccurrencesOfString:hexValue withString:convertedValue];
			}
		}

		range = [value rangeOfString:@"$00"];
	}
	return value;
}

I know this probably does not get the UTF-16 characters, but in my case I (hope to) know they won’t use them.

Well, that’s about it. Not sure if anyone can use this, but I do .

So I looked in queueing the downloads and tried (ofcourse) writing my own QueueHandler class. After I written and spend a couple of hours bughunting/testing my QueueuHandler, I came to the awesome idea to see what the iPhone SDK supplies for this kind of jobs (you DO read my sarcasm, dont you?).

I am using ASIHTTPRequest for my web-requests in WallPaper. I will just show you how I queue my downloads and when the download finishes, I put the image in a predefined and created UIImageView.

I first declare a couple of variables in my .h file.

NSMutableArray* downloadQueue;
NSOperationQueue* queue;

I added some UIImageView’s to a view and I put them and the download URL in a NSMutableDictionary, like this:

NSMutableDictionary* threadArguments = [[NSMutableDictionary alloc] init];

[threadArguments setObject:myUrl forKey:@"url"];
[threadArguments setObject:myImageView forKey:@"iv"];

[self addToDownloadQueue:threadArguments];

The addToDownloadQueue method does something like this after that (threadArguments is the parameter the method is receiving).

// Add the object to the NSMutableArray I got stored.
[downloadQueue addObject:threadArguments];
if (!queue)
{
	queue = [[NSOperationQueue alloc] init];
	[queue setMaxConcurrentOperationCount:1];
}

NSString* threadUrl = [threadArguments valueForKey:@"url"];
NSURL* downloadUrl = [NSURL URLWithString:threadUrl];
ASIHTTPRequest* request = [ASIHTTPRequest requestWithURL:downloadUrl];
[request setDelegate:self];
[request setDidFinishSelector:@selector(downloadDone:)];
[request setDidFailSelector:@selector(downloadFailed:)];

I put the MaxConcurrentOperationCount on 1 to make sure the application sends the requests for thumbnails one by one (going easy on your bandwidth and on my server).

Now we need to implement the FinishSelector and the FailSelector methods to catch the downloads that are finished and put the downloaded image in the pre-created UIImageView.

- (void)downloadFailed:(ASIHTTPRequest *)request
{
	NSLog(@"Downloading failed?");
}

- (void)downloadDone:(ASIHTTPRequest *)request
{
	NSString* downloadUrl = [request.url absoluteString];

	NSMutableDictionary* foundObj = nil;

	for (NSMutableDictionary* dict in downloadQueue)
	{
		NSString* queueUrl = [dict valueForKey:@"url"];

		if ([downloadUrl isEqualToString:queueUrl])
		{
			UIImageView* iv = (UIImageView*)[dict valueForKey:@"iv"];
			NSData* imageData = request.rawResponseData;

			if (iv != nil)
				iv.image = [UIImage imageWithData:imageData];

			foundObj = dict;
		}
	}

	if (foundObj != nil)
		[downloadQueue removeObject:foundObj];
}

*Ok, somehow my code syntax highlighting screws up the indenting.*

Well, I hope you can use something of my weird code.