Creating a Jump action - ios7

Question

I'm working in spritekit/IOS where I have a button that runs an action when it is clicked. The button works fine, but my action is terrible. On click I run this action.
actionMove=[SKAction moveTo:CGPointMake(300,300)duration:2.0];
Which then causes my sprite does a spinning flying kick too that location. I was needed a little help cause I tried replacing the y axis with
_sprite.position+10
But it gives me an error.
Thanks

Answer 1

What you need is the action moveByX:y:duration:...
Sort of.
You can do this...
SKAction *rise = [SKAction moveByX:0 y:10 duration:1];
SKAction *fall = [SKAction moveByX:0 y:-10 duration:1];
SKAction *jump = [SKAction sequence:#[rise, fall]];
Then you can run the jump action on your sprite.
This will move the sprite up by 10 points over 1 second and then down by 10 points over 1 second.
However, it will not look like a jump. It will not accelerate or anything.
If you are including something like a jump in your game then you would normally want to have some sort of collision detection with the floor and use forces to move your sprite instead of actions.
Collision detection method
Sprite Kit Physics Engine
There are two general ways you could do this. The easiest (although longest learning curve) is to use SKPhysicsBody and the built in physics engine in SpriteKit.
You would add a SKPhysicsBody to your character and a boundary SKPhysicsBody to the floor.
Then to make the character jump you would use something like...
[character.physicsBody applyImpulse:CGVectorMake(0, 1)];
This will apply an immediate force to the character so it "jumps" in the air. Then with the physics engine you have built in gravity and so the character will start to slow down and fall until it hits the floor again.
There is a bit of setup for this (less than you would think) but once the setup is done the rest is VERY VERY VERY simple.
Manually
To do it manually is another case. This requires no setup but a LOT of maths. The way this works is to use the update: function and then each update cycle calculate what the velocity and position of the character is and to update the position accordingly.
You really don't want to do this though.
Make things really easy for yourself by adding SKPhysicsBody to the things that need to collide (the character and the floor) and then exploit the gravity and applyImpulse. It will make it much easier, it will perform faster and it will look a million times better :D

Answer 2

There you go :
CGPoint pos = _sprite.position;
pos.y = pos.y + 10;
_sprite.position = pos;

Answer 3

If you are going to use force (and physics) to move your player then using impulse will give you better results:
_sprite.physicsBody applyImpulse:CGVectorMake(0, <value>);
The above depends on a number of factors, including gravity value and the mass of the _sprite.physicsBody. Experimenting is the best way to figure out what works here.

Answer 4

If you are not using physics you can use the followPath action and easing to get a somewhat realistic jumping effect (similar to cocos2d's jump to action). A simple example of how this can be implemented as a category method on SKAction:
+ (SKAction *)jumpWithStartPoint:(CGPoint)startPoint endPoint:(CGPoint)endPoint height:(CGFloat)height {
UIBezierPath *bezierPath = [[UIBezierPath alloc] init];
[bezierPath moveToPoint:startPoint];
CGPoint peak = CGPointMake(endPoint.x - startPoint.x, startPoint.y + height);
[bezierPath addCurveToPoint:endPoint controlPoint1:peak controlPoint2:peak];
SKAction *jumpAction = [SKAction followPath:bezierPath.CGPath asOffset:NO orientToPath:NO duration:.5f];
jumpAction.timingMode = SKActionTimingEaseIn;
return jumpAction;
}