bug with regular collisions in spriteKit - ios

Question

Im making a very simple jumping game. When my "hero" collides with the ground it calls didBeginContact and make a jump. Pretty basic but it doesn't work well because after a while (sometimes sooner, sometimes later...) it stop working as you can see. I would like to know if Im doing something wrong or if there is a better way to do it, or if there is a known bug in spriteKit Id never heard of...
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#interface XYZWorld1()
#property (nonatomic) SKSpriteNode *hero;
#property (nonatomic) SKSpriteNode *groundPhysics;
#end
#implementation XYZWorld1
static const uint32_t ground = 0x2 << 2;
static const uint32_t bee = 0x3 << 3;
Method to create the ground:
-(SKSpriteNode*)createGroundxPos:(float)x yPos:(float)y width:(CGFloat)width height:(CGFloat)height
{
SKSpriteNode *ground = [SKSpriteNode spriteNodeWithColor:[UIColor colorWithHue:1 saturation:1 brightness:1 alpha:1] size:CGSizeMake(width, height)];
SKPhysicsBody *groundFisica =[SKPhysicsBody bodyWithRectangleOfSize:ground.size];
[ground setName:#"ground"];
[groundFisica setDynamic:NO];
[groundFisica setAffectedByGravity:NO];
[groundFisica setAllowsRotation:NO];
[groundFisica setRestitution:0];
[groundFisica setUsesPreciseCollisionDetection:YES];
[groundFisica setCategoryBitMask:ground];
[groundFisica setContactTestBitMask:bee];
[groundFisica setCollisionBitMask:bee];
ground.physicsBody = groundFisica;
[ground setPosition:CGPointMake(x, y)];
return ground;
}
Method to create hero
-(SKSpriteNode*)crearHero
{
SKTexture *temp = _heroWalkingFrames[0];
SKSpriteNode *hero = [SKSpriteNode spriteNodeWithTexture:temp];
hero.name = #"hero";
hero.zPosition = 1;
if(IS_IPHONE_5){
[hero setPosition:CGPointMake(100, 280)];
}
else {
[hero setPosition:CGPointMake(100, 220)];
}
[hero setSize:CGSizeMake(25, 25)];
hero.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(23, 24)];
[hero.physicsBody setDensity:0.95];
[hero.physicsBody setDynamic:YES];
[hero.physicsBody setAffectedByGravity:YES];
[hero.physicsBody setAllowsRotation:NO];
[hero.physicsBody setUsesPreciseCollisionDetection:YES];
[hero.physicsBody setRestitution:0];
[hero.physicsBody setVelocity:CGVectorMake(0, 0)];
return hero;
}
Method to preload all the stuff before the game starts:
-(void)preloadAssets
{
//hero
_heroWalkingFrames = [self cargarArrayAtlas:#"astroJump.atlas" imageName:#"astronautaJump_000"];
_hero = [self crearHero];
_hero.physicsBody.categoryBitMask = bee;
_hero.physicsBody.collisionBitMask = bee | cubico | ground | bicho ;
_hero.physicsBody.contactTestBitMask = bee | cubico | ground | bicho ;
//Ground
_groundPhysics = [self createGroundxPos:100 yPos:142 width:42 height:23.25];
}
Method called when two bodies first contact each other:
-(void) didBeginContact:(SKPhysicsContact *)contact
{
//if hero collides with ground
if((contact.bodyA.categoryBitMask == bee && contact.bodyB.categoryBitMask == ground) ||
(contact.bodyA.categoryBitMask == ground && contact.bodyB.categoryBitMask == bee) )
{
if(_jumping == NO && _groundPhysics.position.y+_groundPhysics.size.height/2<=_hero.position.y-11.5)
{
[self jumping];
}
}
}
Method called to do the jump:
-(void)jumping{
//Play sound file
[self runAction:self.jumpSound withKey:#"jumpSound"];
if(IS_IPHONE_5){
_diferencia=(164 * 9)/_hero.position.y;
}else{
_diferencia=(164 * 7)/_hero.position.y;
}
[_hero.physicsBody applyImpulse:CGVectorMake(0,_diferencia)];
_jumping = YES;
[_hero removeActionForKey:#"astroJump"];
[self astroJump];
}
-(void)astroJump
{
//runAction animation method
[_hero runAction:[SKAction animateWithTextures:_heroWalkingFrames
timePerFrame:0.05f
resize:NO
restore:NO] withKey:#"astroJump"];
return;
}
the boolean (self.jumping) from the if sentence, in update and initGameContent:
-(void)update:(CFTimeInterval)currentTime
{
if(_hero.physicsBody.velocity.dy < 0 )_jumping = NO;
}
-(void)initGameContent
{
_jumping = NO;

Answer 1

You might want to make sure you reset your players position to be above the ground when contact with the ground is detected. Otherwise the player could still be in contact with the ground when [self jumping]; is called which can sometimes result in the player being "stuck". I've seen similar issues in my games when doing collision detection. The code below shows what you could do to resolve this issue.
if (_jumping == NO && _groundPhysics.position.y+_groundPhysics.size.height/2<=_hero.position.y-11.5)
{
_hero.position.y = _groundPhysics.position.y + _groundPhysics.size.height/2 + 1;
[self jumping];
}

Answer 2

I finally found a way to fix it. I've changed the size of physicbody.size.y to the same as his spriteNode.y and the bug has gone.