检测函数：
- (void)update:(ccTime)dt {
NSLog(@"start......")
NSMutableArray *projectilesToDelete = [[NSMutableArray alloc] init];
for (CCSprite *projectile in _projectiles) {
CGRect projectileRect = CGRectMake(
projectile.position.x - (projectile.contentSize.width/2),
projectile.position.y - (projectile.contentSize.height/2),
projectile.contentSize.width,
projectile.contentSize.height);
NSMutableArray *targetsToDelete = [[NSMutableArray alloc] init];
for (CCSprite *target in _targets) {
CGRect targetRect = CGRectMake(
target.position.x - (target.contentSize.width/2),
target.position.y - (target.contentSize.height/2),
target.contentSize.width,
target.contentSize.height);
if (CGRectIntersectsRect(projectileRect, targetRect)) {
[targetsToDelete addObject:target];
NSLog(@"check......")
}
}
for (CCSprite *target in targetsToDelete) {
[_targets removeObject:target];
[self removeChild:target cleanup:YES];
}
if (targetsToDelete.count >0) {
[projectilesToDelete addObject:projectile];
}
[targetsToDelete release];
}
for (CCSprite *projectile in projectilesToDelete) {
[_projectiles removeObject:projectile];
[self removeChild:projectile cleanup:YES];
}
[projectilesToDelete release];
NSLog(@"end......")
}
说明：我们仅仅通过遍历projectiles和targets数组，为每个projectile和target创建边界矩形，然后使用CGRectIntersectsRect来检测碰撞。如果发现有碰撞了，我们就从场景中移除精灵，同时也把它移除出数组。
注意：我们不得不添加一个toDelete数组，因为我们不能在遍历一个数组的时候去删除数组中的对象。
正常的运行结果是这样的：
start....
check....
....
end....
如果在遍历一个数组时删除数组中的对象的话，程序不会报错，但是逻辑就不对了，如下面的写法：
if (CGRectIntersectsRect(projectileRect, targetRect)) {'
NSLog(@"check.....")
[_targets removeObject:target];
[self removeChild:target cleanup:YES];
[_projectiles removeObject:projectile];
[self removeChild:projectile cleanup:YES];
}
调试函数运行的结果是这样的
start....
check....
....
start....
end....
这肯定就不对了