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Archive for the ‘UIKit’ Category

Core Animation stops animation on app relaunch

19 Sep

On one of my projects I discovered a bug in a never-ending animation I had set up. Whenever the app was suspended (such as when you multitask and open another app), on relaunching the app the animation was frozen. After some investigating, I discovered that you need to set a flag on the CABasicAnimation called removedOnCompletion to NO otherwise the animation will get cleaned up when it gets suspended.

CABasicAnimation *dartWiggleAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
dartWiggleAnimation.fromValue =
   [NSValue valueWithCGPoint:CGPointMake(self.center.x-DART_WIGGLE_HALF, self.center.y+DART_CENTER_H_OFFSET)];
dartWiggleAnimation.toValue =
   [NSValue valueWithCGPoint:CGPointMake(self.center.x+DART_WIGGLE_HALF, self.center.y+DART_CENTER_H_OFFSET)];
dartWiggleAnimation.timingFunction =
   [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut]; 
 
dartWiggleAnimation.duration = 0.4;
dartWiggleAnimation.repeatCount = HUGE_VALF;
dartWiggleAnimation.autoreverses = YES;
dartWiggleAnimation.removedOnCompletion = NO;
 
[[nextDart layer] addAnimation:dartWiggleAnimation forKey:@"dartWiggle"];

Does this seem like a bug or a feature?

 
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Posted in Core Animation, Programming, UIKit

 

Custom fonts on iPad and iPhone

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: -

  • OpenType Format (OTF)
  • TrueType Format (TTF)

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.

Xcode Screenshot

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.
 
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Posted in Cocoa, Programming, UIKit