Audio and Labels - Learn SpriteBuilder for iOS Game Development - page 377

we'll be getting at next. A playEffect volume of 1.0 means the audio file is played at
the same volume as effectsVolume .
The pitch is randomized between 0.8 and 1.3 to create greater sound variety without
having to use multiple effects. This also shows an example of how to generate floating-
point numbers with arc4random_uniform . If you divide a value in the range of 0 to
49 and divide it by 100.0, you get a value in the range of 0.0 to 0.49. Note that it's import-
ant to write 100.0 with the dot or casting the value: (CGFloat)100 . If the divisor is
simply written as 100 , it is an integer division that always results in 0 .
To quickly test this sound effect playback, add the highlighted line in Listing 11-7 to the
ccPhysicsCollisionBegin: method that is called when the player collides with a
spring object.
Listing 11-7 . Playing a sound effect when colliding with springs
-(BOOL) ccPhysicsCollisionBegin:(CCPhysicsCollisionPair
*)pair
player:(CCNode *)player
spring:(SpringBoard *)spring
{
[spring letGo];
[self playCollisionSoundWithPair:pair];
return YES;
}
You should also add two more ccPhysicsCollisionBegin methods, pairing the
player with obstacles and gears. Add the code in Listing 11-8 below the other ccPhys-
icsCollisionBegin methods.
Listing 11-8 . Playing sound effects when colliding with obstacles and gears
-(BOOL) ccPhysicsCollisionBegin:(CCPhysicsCollisionPair
*)pair
player:(CCNode *)player
obstacle:(CCNode*)obstacle
{
[self playCollisionSoundWithPair:pair];
return YES;