Distance between p1 and p2:

CGFloat xDist = (p2.x - p1.x); CGFloat yDist = (p2.y - p1.y); CGFloat distance = sqrt((xDist * xDist) + (yDist * yDist));

Background: Pythagorean theorem

Edit: if you only need to calculate if the distance between the points increases or decreases, you can omit the sqrt() which will make it a little faster.

This is how you play and stop sound effects in cocos2d

Here is how to determine the device type.\r\n\r\nHow to use it.\r\n\r\nUIDeviceHardware *h=[[UIDeviceHardware alloc] init];\r\n[self setDeviceModel:[h platformString]]; \r\n[h release];

Here is how you add a shadow to a UILabel on the iPhone.

Add the following framework "AddressBook.framework" to your project

Make sure to import these header files.

01-Dec-2008 10:22 PM Tom Saxton: I looked at this bug some more, and it seems to be an issue with the tabbar.

If you call UIActionSheet's [sheet showInView:self.view] from a view controller that is a child of a UITabViewController, then the hit testing on the cancel button fails in that portion of the UIActionSheet that lies above the tabbar's view.

If you instead pass in the UITabBarController's view, then the UIActionSheet acts as expected.

NOTE: in iPhone OS 2.1 and earlier, the UIActionSheet came up from the top of the tab bar when you pass the child view, but in 2.2, it comes up from the bottom of the tab bar, and thus covers the tab view.

This might look complicated but actually it was easy than what I though to integrate. I'm using it with Core Data, but I'm sure you can use it with any data type.