For as active as iPhone application development community is, achieving success in iTunes has been an elusive affair for those who participate in this vertical.  The two main obstacles presented to anyone who wants to create an iPhone applications are: one, finding resources/developers with the right skill set; and two, marketing the application after the application has been submitted.  The bad news is Apple keeps iTunes a black box.  Unless your application has been reviewed or mentioned on review sites or blogs, no one will be able to find your application outside of iTunes.  This makes marketing your application relatively difficult.  Here’s the good news: the cost to build an iPhone application should come down substantially as it no longer requires a developer with an exclusive knowledge to a specific technology to build an application for iPhone.

When Apple first announced to openly accept applications from developers, the prerequisite for the developer is a somewhat extensive knowledge in a language called “Objective-C.”  For a short while, it would seem as though the developers who could produce Objective-C codes were superstars that also came with a superstar price tag.  Such stardom, however, did not last.  When PhoneGap was introduced as an open source development tool for iPhone via JavaScript, the web development community devoured it like salmon to a hungry bear.  Shortly after PhoneGap’s success, Mono framework was released in the commercial sector that provided the necessary development tools to the vast number of C# developers across multiple platforms.  And to unhinge the final bar from the floodgates, Adobe has just announced that the next release of Flash is capable of compiling a flash project directly into native iPhone application.  Simply put, a project can go from design to finish without even being touched by a developer.

The implication for this phenomenon is a curious one: how will Apple respond to the rush of new applications when the floodgates are finally open?  Will Apple still be able to keep its manual review process intact?  When the market is saturated with developers and applications, will Apple be able to to maintain iTunes exclusive distribution channel and continue to motivate merchants to participate?

How all of this will affect Apple or iPhone developers is yet to be seen.  However, one thing that seems to be true is that when given enough demands, people will find ways to liberate a technology regardless of how businesses are structured around it.

Introduction

Hello everyone, welcome to my third screeencast. This screencast is the result of a request made in the comments of my first post. I am going to be covering many topics in this post. But the general idea of the app we will build is that it will use an XML file online to get the URL and title of a given picture. For each URL and Title pair a view will be created with a UIImageView showing the image and a UILabel showing the title. Each of these views will be placed in a UIScrollView to flip through, like th functinoality of the Photos app.

Skill Level Medium

This app is going to require a decent amount of experience with Objective C and xCode. Also some minimal understanding of XML and XML schema/structure would be valuable.

Source Code

Available Here

Screencast

I film myself coding out the entire sample project for each post. I personally think going through the Screencast is the best way to learn. But feel free to look through the slides and text if that suites you better.

iCodeBlog: Using NSXMLParser to pull UIImages off the Web from Collin Ruffenach on Vimeo.

SCREENCAST ADDITION

Adding a final line to layoutSubviews should be:

     [scrollview setFrame:workingFrame];

this will stop the scroll view from bouncing up and down.

Tutorial

iCodeBlogXMLImagesViewController.h:

@interface iCodeBlogXMLImagesViewController : UIViewController
{
	IBOutlet UIScrollView *scrollview;
}

@property (nonatomic, retain) IBOutlet UIScrollView *scrollview;

iCodeBlogXMLImagesViewController.m

@synthesize scrollview;

iCodeBlogXMLView.h:

@interface iCodeBlogXMLView : UIView
{
	IBOutlet UIImageView *imageView;
	IBOutlet UILabel *title;
}

@property (nonatomic, retain) IBOutlet UIImageView *imageView;
@property (nonatomic, retain) IBOutlet UILabel *title;

@end

iCodeBlogXMLView.m

@synthesize imageView;
@synthesize title;

iCodeBlogXMLElement.h:

@interface iCodeBlogXMLElement : NSObject
{
	UIImage *image;
	NSString *imageTitle;
}

@property (nonatomic, retain) UIImage *image;
@property (nonatomic, retain) NSString *imageTitle;

@end

iCodeBlogXMLElement.m

@synthesize image;
@synthesize imageTitle;

iCodeBlogXMLImagesViewController.h:

#import <UIKit/UIKit.h>
#import "iCodeBlogXMLElement.h"
#import "iCodeBlogXMLView.h"

@interface iCodeBlogXMLImagesViewController : UIViewController
{
	IBOutlet UIScrollView *scrollview;

	NSXMLParser *parser;
	NSMutableString *currentAttribute;
	NSMutableArray *xmlElementObjects;

	iCodeBlogXMLElement *tempElement;
}

@property (nonatomic, retain) IBOutlet UIScrollView *scrollview;

@property (nonatomic, retain) NSXMLParser *parser;
@property (nonatomic, retain) NSMutableString *currentAttribute;
@property (nonatomic, retain) NSMutableArray *xmlElementObjects;

@property (nonatomic, retain) iCodeBlogXMLElement *tempElement;

-(void)layoutSubview;

@end

iCodeBlogXMLImagesViewController.m

@implementation iCodeBlogXMLImagesViewController

@synthesize scrollview;
@synthesize parser;
@synthesize currentAttribute;
@synthesize xmlElementObjects;
@synthesize tempElement;

...

- (void)viewDidLoad
{
    [super viewDidLoad];

	xmlElementObjects = [[NSMutableArray alloc] init];

	parser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://losectrl-gaincommand.com/iCodeBlogHelper/Tutorial3/iCodeBlogImageXML.xml"]];
	[parser setDelegate:self];
	[parser parse];
}

...

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{

}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{

}

iCodeBlogXMLImagesViewController.m

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
	if(![elementName compare:@"PictureInfo"])
	{
		tempElement = [[iCodeBlogXMLElement alloc] init];
	}

	else if(![elementName compare:@"imageURL"])
	{
		currentAttribute = [NSMutableString string];
	}

	else if(![elementName compare:@"imageTitle"])
	{
		currentAttribute = [NSMutableString string];
	}
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
	if(![elementName compare:@"PictureInfo"])
	{
		[xmlElementObjects addObject:tempElement];
	}

	else if(![elementName compare:@"imageURL"])
	{
		NSURL *imageURL = [NSURL URLWithString:currentAttribute];
		NSData *data =  [NSData dataWithContentsOfURL:imageURL];
		UIImage *image = [[UIImage alloc] initWithData:data];

		[tempElement setImage:image];
	}

	else if(![elementName compare:@"imageTitle"])
	{
		NSLog(@"The image title is %@", currentAttribute);
		[tempElement setImageTitle:currentAttribute];
	}

	else if(![elementName compare:@"Pictures"])
	{
		[self layoutSubview];
	}
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
	if(self.currentAttribute)
	{
		[self.currentAttribute appendString:string];
	}
}

iCodeBlogXMLImagesViewController.m

-(void)layoutSubview
{
	CGRect workingFrame;

	workingFrame.origin.x = 0;
	workingFrame.origin.y = 0;
	workingFrame.size.height = 480;
	workingFrame.size.width = 320;

	iCodeBlogXMLView *myView;

	for(iCodeBlogXMLElement *element in [self xmlElementObjects])
	{
		myView = [[iCodeBlogXMLView alloc] initWithFrame:workingFrame];

		NSLog(@"Element title is: %@", [element imageTitle]);

		NSArray *topLeveObjects = [[NSBundle mainBundle] loadNibNamed:@"iCodeBlogXMLView" owner:nil options:nil];

		for(id currentObject in topLeveObjects)
		{
			if([currentObject isKindOfClass:[iCodeBlogXMLView class]])
			{
				myView = (iCodeBlogXMLView *)currentObject;
			}
		}

		[[myView imageView] setImage:[element image]];
		[[myView title] setText:[element imageTitle]];
		[myView setFrame:workingFrame];

		[scrollview addSubview:myView];

		workingFrame.origin.x = workingFrame.origin.x + 320;
	}

	workingFrame.size.width = workingFrame.origin.x;
	[scrollview setContentSize:workingFrame.size];

	workingFrame.origin.x = 0;
	workingFrame.origin.y = 0;
	workingFrame.size.width = 320;
	workingFrame.size.height = 480;
}

iCodeBlogXMLImagesViewController.m

	parser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://losectrl-gaincommand.com/iCodeBlogHelper/Tutorial3/iCodeBlogImageXMLB.xml"]];

Hey everyone, welcome to my first of many screencasts coming in the next few weeks. Today I am going to show you how to layout a UITableViewCell in Interface Builder and have a UITableView populate with those type of cells. I am adopting a new structure for my screencasts which will be 5 or so mintues of keynote slides giving background info followed by 20 – 25 mintues of step by step development. The entire video will be directly below this paragraph, but scrolling down you will see a text based step by step of the whole tutorial as well. Hope you guys enjoy.

Skill Level MEDIUM

Here is a link to the screencast to watch. We are working on getting an embedded version in, but I figure this is basically just as functional. Have fun!

Custom UITableViewCell Screencast Video

Source Code

Available Here

Background Information

Building The App

Step 1

This step shouldn’t require any extra information.

Step 2

Step 3

In CustomTableCellTutorialViewController.m you must define the two required UITableViewDataSource methods. These methods will fill up the table view with data. For now we will put in dummy data just to make sure all of our connections are working.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

return 10;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

static NSString *CellIdentifier = @”Cell”;

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil){

cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];

}

[cell setText:[NSString stringWithFormat:@"I am cell %d", indexPath.row]];

return cell;

}

Step 4

Here you will need to be in xCode and go to File -> New File…

Select Objective C Class and make sure it is a UITableViewCell subclass, depending on your version of the SDK selecting this will differ. Look around and you will find it, call it iCodeBlogCustomCell. With this done enter these IBOutlets in the iCodeBlogCustomCell.h file enter the following IBOutlets:

IBOutlet UILabel *articleName;
IBOutlet UILabel *authorName;
IBOutlet UILabel *date;

IBOutlet UIImageView *imageView;
IBOutlet UIView *viewForBackground;

Add the @property and synthesize them in the main.

Step 5

This step does not require and code but does require a lot of work in Interface Builder. I highly recommend you watch the screencast to see the step by step procedure here. Essentially what I do is create a new View XIB file. Opening this, I delete the standard UIView in the XIB and drag a UITableViewCell from my library into my document window. I assign the UITableViewCell to be of type iCodeBlogCustomCell. With this done layout the interface with the proper elements and hook them up by right clicking on the UITableViewCell in the document window.

Step 6

This is where the real magic is. We are going to return to CustomTableCellTutorialViewController.m and edit the UITableViewDataSource methods we implemented earlier. The code I use has me putting in 4 separate PNG files that I add to my project. You can find your own to put inside the cells. Make sure the UIImageView inside the cell is set for Aspect Fit so you don’t have to worry about resizing the images.  The functions should be changed to be:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 100;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @”iCodeBlogCustomCell”;

iCodeBlogCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil){
NSLog(@”New Cell Made”);

NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@”iCodeBlogCustomCell” owner:nil options:nil];

for(id currentObject in topLevelObjects)
{
if([currentObject isKindOfClass:[iCodeBlogCustomCell class]])
{
cell = (iCodeBlogCustomCell *)currentObject;
break;
}
}
}

if(indexPath.row % 4 == 0)
{
[[cell authorName] setText:@”Collin Ruffenach”];
[[cell articleName] setText:@”Test Article 1″];
[[cell date] setText:@”May 5th, 2009″];
[[cell imageView] setImage:[UIImage imageNamed:@"1.png"]];
}

else if(indexPath.row % 4 == 1)
{
[[cell authorName] setText:@”Steve Jobs”];
[[cell articleName] setText:@”Why iPhone will rule the world”];
[[cell date] setText:@”May 5th, 2010″];
[[cell imageView] setImage:[UIImage imageNamed:@"2.png"]];
}

else if(indexPath.row % 4 == 2)
{
[[cell authorName] setText:@”The Woz”];
[[cell articleName] setText:@”Why I’m coming back to Apple”];
[[cell date] setText:@”May 5th, 2012″];
[[cell imageView] setImage:[UIImage imageNamed:@"3.png"]];
}

else if(indexPath.row % 4 == 3)

{
[[cell authorName] setText:@”Aaron Hillegass”];
[[cell articleName] setText:@”Cocoa: A Brief Introduction”];
[[cell date] setText:@”May 5th, 2004″];
[[cell imageView] setImage:[UIImage imageNamed:@"4.png"]];

}

return cell;
}

The End

So that is it for my first new post. I will be doing many more. Let me know your thoughts on this format in the comments. If you see anything organization wise that you think should be changed/add/removed let me know. Good Luck!

]]> http://icodeblog.com/2009/05/24/custom-uitableviewcell-using-interface-builder/feed/ 79 http://icodeblog.com/2008/11/03/finding-substrings-in-objective-c/ http://icodeblog.com/2008/11/03/finding-substrings-in-objective-c/#comments Tue, 04 Nov 2008 05:57:00 +0000 josh http://icodeblog.com/2008/11/03/finding-substrings-in-objective-c/ It’s times like this, that I miss ruby. I’m checking a url to see if it has a substring. It would be so easy if this was ruby: absolute_url.match(/my regex/).any? In Objective C, you have to use rangeOfString which returns [...]]]>

It’s times like this, that I miss ruby.

I’m checking a url to see if it has a substring. It would be so easy if this was ruby:

absolute_url.match(/my regex/).any?

In Objective C, you have to use rangeOfString which returns a range. If I were to run this on the string “the quick brown fox” with an argument of “brown” it would return {10,14}. If it’s not found, it would return {NSNotFound, 0}. Let’s use that to check to see if the range was found. We’ll use NSMakeRange to create the NSNotFound range and NSEqualRanges to compare them:

if(NSEqualRanges(NSMakeRange(NSNotFound, 0), [absoluteURL rangeOfString:@"my_substring"])){   NSLog(@"my_substring not found in absoluteURL %@", absoluteURL);}