the austrian iphone/ipad development

to start iphone apps from your app is very simple. you only have to call an url. for example for “http://” safari is respondig:

http://www.google.com -> opens safari

with “fb://” the facebook app is responsible.

to open such an url you only have to write:

[[UIApplication sharedApplication]
openURL:[NSURL URLWithString:@"http://....."]];

for information see:

http://wiki.akosma.com/IPhone_URL_Schemes (big collection of possible url schemes)

http://iphonedevtools.com/?p=302 (for facebook app)

to determine if you can open a specific app on the iphone in cocoa like facebook with “fb://” just call:

if ([[UIApplication sharedApplication] canOpenURL:url])

the UIView class on the iPhone offers some very simple and mighty class methods that allow you to animate your UIView objects with only a few lines of code.

the animations you can create with these methods are created in “animation blocks”. to open a new animation block you use the method beginAnimations:context: and to close the block call the methods commitAnimations. within this aimation block you can specify how your UIView objects should be animated. this way, you can animate for example changes of the views size, its location or its transparency. you do this by changing the values of the corresponding propertys of your view. some of the propertys whose value changes can be animated are:

• frame
• bounds
• center
• alpha
• etc.

additionally you can specify how the animations created in an animation block behave:
you can set the duration with the methods setAnimationDuration, you can specify the way the animation accelerates and decelerates with the method setAnimationCurve:.

and now, an example for a typical animation – let’s say you have an UIView object-variable named yourView and you want to fade it out smoothly with an animation, that means that its alpha value will be 0 at the end of the animation and it will be invisible:

[UIView beginAnimations:nil context:UIViewGetCurrentContext()];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationDuration:1.0];

// here you specify the value the view's property should have
// at the end of the animation
yourView.alpha = 0.0;

[UIView commitAnimations];

for now that is enough for you for building your own animations an get a mighty tool to animate your own user interfaces in a very simple and quick way.

do you know the proximity sensor? this is some nice ir-sensor on the left from the headspeakers.

just the idea behind this – a new user interaction with proximity sensor

fingers do not prevent view to screen. screen is free. if you produce a reaction game this would be a nice user interaction. we are going to produce such a small game.

some sample code:

UIDevice *device = [UIDevice currentDevice];
[device setProximityMonitoringEnabled:TRUE];
if ([device isProximityMonitoringEnabled] == FALSE) {
   NSLog(@"Proximity Sensor not available");
   return YES;
}

this means: if the proximitymonitorenabled attribute is true after setting it to true you have sensor support. otherwise after setting to true it is not available. after this you can do:

[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(proximitySensorChanged:)
name:UIDeviceProximityStateDidChangeNotification
object:nil];

now you can define a method named: proximitysensorchanged and receive a notification if it user moves away from the sensor. just the method:

- (void) proximitySensorChanged: (NSNotification *) notification {
   [[UIDevice currentDevice] setProximityMonitoringEnabled:FALSE];
   UIDevice *device = [notification object];
   NSLog(@"Proximity: %i", device.proximityState);
}

it is NO possible to cancel the process of darkening the screen (currently).