It’s now been just over 3 weeks since the torrent of information unleashed at Apple’s World Wide Developer Conference refreshingly drenched the brains of designers, developers and engineers. I’ve resisted blogging about the public announcements to fully let the impact soak in and gage everyone’s reactions but now feels like a good time to talk about where the future of computing is heading.
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Archive for the ‘Cocoa’ Category
WWDC Update: 5 key points for iPhone apps
Posted on Tuesday, July 5, 2011
05
Jul
Calculating UNIX file permissions
Posted on Friday, June 3, 2011
03
Jun
A few years ago I wrote a simple but handy Mac app that calculates unix file permissions using a matrix of check boxes. I wrote it because I wanted to better understand how those octal values get calculated and to expand my experience of writing Mac apps.
I was also learning some crazy assembly code at the time too so I was also making sense of putting bitwise operations to task. Rather than let this code languish on my hard drive, I thought I’d share…
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Core Data Objects in Wrong Sections
Posted on Monday, October 18, 2010
18
Oct
NSFetchedResultsController is a really handy class. Use one of the default Core Data templates in Xcode and you’ll very quickly have a nice list of managed objects in a table view. With a few more lines of code you can get the NSFetchedResultsController to group your objects by sections. You do this by specifying a key-path in the class’s constructor method but there is another step that if overlooked will cause some confusion.
In a sample app I’ve created a food table that lists food in categories.
FetchedResultsController method grouping sections using a key-path:
- (NSFetchedResultsController *)fetchedResultsController { if (fetchedResultsController != nil) { return fetchedResultsController; } // Create and configure a fetch request with the food entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"RWFood" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // Create the sort descriptors array. NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:nameDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; // Create and initialize the fetch results controller. NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"category" cacheName:@"Food"]; self.fetchedResultsController = aFetchedResultsController; fetchedResultsController.delegate = self; // Memory management. [aFetchedResultsController release]; [fetchRequest release]; [nameDescriptor release]; [sortDescriptors release]; return fetchedResultsController; }
Save and quit the app a few times and you’ll see the objects seem to be in the wrong sections. If you look closer you’ll see that the objects are actually sorted in ascending name order. On looking at the code, it seems this is exactly what we asked the program to do! After some testing it also seems to show up more often if the table is a grouped one.
As per the docs, after you specify a key-path to group each section with you also need to make sure the first sort descriptor is sorting this key-path. Add a sort descriptor and everything will work as expected.
Revised fetchedResultsController method with missing sort descriptor:
- (NSFetchedResultsController *)fetchedResultsController { if (fetchedResultsController != nil) { return fetchedResultsController; } // Create and configure a fetch request with the plant entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"RWPlant" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // Create the sort descriptors array. NSSortDescriptor *typeDescriptor = [[NSSortDescriptor alloc] initWithKey:@"type" ascending:YES]; NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:typeDescriptor, nameDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; // Create and initialize the fetch results controller. NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"type" cacheName:@"Plants"]; self.fetchedResultsController = aFetchedResultsController; fetchedResultsController.delegate = self; // Memory management. [aFetchedResultsController release]; [fetchRequest release]; [categoryDescriptor release]; [nameDescriptor release]; [sortDescriptors release]; return fetchedResultsController; }
Quick Spreadsheet to plist Technique
Posted on Tuesday, September 21, 2010
21
Sep
Imagine you have a huge list of names in a spreadsheet and you’d like to get this data into an Apple plist file to use in your iPhone/Mac app or import into a Core Data model. Such a long list of data would take forever to cut and paste so here is a really quick way to build that plist.
Custom fonts on iPad and iPhone
Posted on Wednesday, August 18, 2010
18
Aug
Just incase you didn’t realise, with iOS 3.2 (iPad) and above you can load in custom fonts and use them with a standard UIFont object. There are a few catches… The font must be in the following format: -
Once you’ve dragged your chosen font file into an Xcode project, the next step is to add a line into the application’s Info.plist file. Add a new key UIAppFonts and make it an array. Expand the array and add a new string for each font, making the string the file’s full name including an extension.
You’re all set up now to use the font. That would be great if you knew which font it was! Here is a great little snippet for looping through all the fonts loaded into the system. Scan through the list and find your font.
// Get all the fonts on the system NSArray *familyNames = [UIFont familyNames]; for( NSString *familyName in familyNames ){ printf( "Family: %s \n", [familyName UTF8String] ); NSArray *fontNames = [UIFont fontNamesForFamilyName:familyName]; for( NSString *fontName in fontNames ){ printf( "\tFont: %s \n", [fontName UTF8String] ); } }
To use your font now, just use the standard UIFont constructor…
self.titleLabel.font = [UIFont fontWithName:@"Inkpen Medium" size:31.0];
Some points to note: -
- You can also use the font inside UIWebViews.
- Interface Builder for XCode 3.2 has a bug that won’t let you choose the font. You have to do it in code.
- Loading in too many fonts will slow your loading time down and will hurt your users’ eyes.
