Hi I am new to Xcode and Swift, right now I am trying to design a game that involves a spaceship as player with alien spaceships.
I ran into a little problem where I am trying to differentiate the movement of the spaceship from the firing of the spaceship.
Basically I used touchesBegan() function to run the function which my spaceship fires, and touchesMoved() function to move the spaceship's x-position.
These are the code:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
pShoot()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches{
let location = touch.location(in: self)
spaceship.run(SKAction.moveTo(x: location.x, duration: 0.5))
}
}
What I am trying to do is to differentiate the clicking or touching indicator and pressed and move indicator, in other words I dont want the spaceship to fire when I am pressed and move on the screen, and I do not want the spaceship to move when I am clicking constantly but at different position. ( touchesMoved() detects changes in touch positions so if I am clicking at different positions spaceship will move which I dont want)
I would like to know what would be the best way of implementing this, thank you.
You could try checking the area that the user pressed and deciding whether or not to move the spaceship depending on the origin of the touch.
How can I avoid a UIButtons .touchDragEnter and .touchDragExit functions from rapid firing? This question demonstrates the issue perfectly, but the only answer does not describe how to work around it. I'm trying to animate a button when the users finger on the button, and animate it again when their finger slides off. Are there any better ways to do this? If not, how should I stop my animation code from firing multiple times when the users finger is right between an .enter and an .exit state?
You could instead track the location of the touch point itself and determine when the touch point moves in and out of the button
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let point = t.location(in: self)
// moving in to the button
if button.frame.contains(point) && !wasInButton {
// trigger animation
wasInButton = true
}
// moving out of the button
if !button.frame.contains(point) && wasInButton {
// trigger animation
wasInButton = false
}
}
}
wasInButton could be a boolean variable set to true when there is a touch down in the button's frame:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let point = t.location(in: self)
if button.frame.contains(point) {
wasInButton = true
// trigger animation
} else {
wasInButton = false
}
}
This would require you to subclass the button's superview. And since you might not want to animate as soon as the point leaves the button's frame (because the user's finger or thumb would still be covering most of the button), you could instead do the hit test in a larger frame that encapsulates your button.
I'm trying to use a gesture recognizer to allow the user to resize a view on the screen by dragging it with one finger... as such, I want to track all changes to the touch. I initially tried to use a PanGestureRecognizer for this, but I've run into an issue when the user touches the view with multiple fingers. I only want to track the first touch (ie the first finger the user places on the screen during a gesture), but I can't find a way to prevent additional touches from interfering with my ability to track the first. My initial solution was to simply set
recognizer.maximumNumberOfTouches = 1
However, this causes the entire gesture to be cancelled in the event of a second touch (I want to continue tracking the first touch in this case). But, of course, not setting this value to 1 causes the gesture to actually track multiple touches. How can I make a gesture recognizer that tracks all changes to only the first touch in the gesture, and isn't cancelled by additional touches on the screen?
From your comments and answer, it sounds like your use of a pan gesture recognizer was always wrong and you were doing something wrong in your action handler. No correct action handler for a pan gesture recognizer would ever use location(in:) for anything. location(in:) gives you a centroid of all touches, which is exactly what you say you don't want — and in any case there is no need to consult it.
If your goal is to drag a view, you use translation(in:).
If your goal is to track the actual location of a particular touch, you use location(ofTouch:in:).
If you discover that a touch is being delivered and you don't want it tracked, call ignore(_:for:).
Here is a UIGestureRecognizer subclass that will track all changes the first touch the user places on the screen at the start of a gesture, and will ignore all other fingers without cancelling the gesture. Note that if you're using functions/properties of the gesture recognizer (such as location(in:)), you'll probably have to override those as well.
class FirstTouchGestureRecognizer: UIGestureRecognizer {
private var firstTouch: UITouch? = nil
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch == nil {
firstTouch = touches.first!
self.state = .began
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch != nil && touches.contains(firstTouch!) {
self.state = .changed
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch != nil && touches.contains(firstTouch!) {
firstTouch = nil
self.state = .ended
}
}
}
Hi I am currently moving a sprite by checking if the button was pressed in touchesBegan and then updating the position in update. I am doing this so that the user does not need to keep pressing the move up/down/left/right etc button over and over. The problem is that sometimes the sprite does not stop moving which im sure is due to this. Does anyone know a better solution to this? For brevity I will show you the way I am taking care of the up button.
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
for touch: AnyObject in touches {
// Get the location of the touch in this scene
let location = touch.locationInNode(self)
// Check if the location of the touch is within the button's bounds
if upButton.containsPoint(location) {
upButtonPressed = true
}
override func update(currentTime: CFTimeInterval) {
if upButtonPressed == true {
ball.position.y += 3
}
I kept it simple here but I do have all the conditions to stop movement in my code. I am simply wondering if there is an easier way to do this with maybe a long press gesture recognizer?
UPDATE: I have solved the problem, and figured out a more simplified way to do this then the answer provided. My solution was to make the velocity of the SPACESHIP equal the distance it was from my finger touch. For faster movement, you can multiply this velocity by a constant. In this case, I used 16. I also got rid of setting lastTouch to nil in the touchesEnd event. That way, the ship will still stop even when I release my finger.
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
if let touch = lastTouch {
myShip.physicsBody.velocity = CGVector(dx: (lastTouch!.x - myShip.position.x) * 16, dy: 0)
}
}
===============================
I have a SPACESHIP node with movement restricted to the X-Axis. When the user PRESSES and HOLDS somewhere on the screen, I want the SPACESHIP to be able to move to the finger's x-coordinate, and not stop moving toward the finger until the finger is RELEASED. If the SPACESHIP is close to the users finger and the users finger is still pressed down, I want it to gradually slow down and stop. I also want this smooth motion to be applied when the SPACESHIP changes direction, starts, and stops.
I am trying to figure out the best way to do this.
So far, I have created the node and it moves correctly, but there is a problem: If I press on the screen and hold down, the ship will eventually cross over my finger and keep moving. This is because the logic to change direction of the ship is only triggered if I move my finger. So essentially, moving my finger over the ship to change the ships' direction works, but if the ship crosses over my still finger, it does't change direction
I need the SPACESHIP node to recognize when it has crossed over my still finger, and either change its direction or stop based on how close it is to my finger.
Here is the relevant code:
Part 1: When the user presses down, find out where the touch is coming from and move myShip (SPACESHIP) accordingly using velocity
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
let touch = touches.anyObject() as UITouch
let touchLocation = touch.locationInNode(self)
if (touchLocation.x < myShip.position.x) {
myShip.xVelocity = -200
} else {
myShip.xVelocity = 200
}
}
Part 2 When the user moves their finger, trigger an event that checks to see if the finger has now moved to the other side of the ship. If so, change direction of the ship.
override func touchesMoved(touches: NSSet!, withEvent event: UIEvent!) {
let touch = touches.anyObject() as UITouch
let touchLocation = touch.locationInNode(self)
//distanceToShip value will eventually be used to figure out when to stop the ship
let xDist: CGFloat = (touchLocation.x - myShip.position.x)
let yDist: CGFloat = (touchLocation.y - myShip.position.y)
let distanceToShip: CGFloat = sqrt((xDist * xDist) + (yDist * yDist))
if (myShip.position.x < touchLocation.x) && (shipLeft == false) {
shipLeft = true
myShip.xVelocity = 200
}
if (myShip.position.x > touchLocation.x) && (shipLeft == true) {
shipLeft = false
myShip.xVelocity = -200
}
}
Part 3 When the user releases their finger from the screen, I want the ship to stop moving.
override func touchesEnded(touches: NSSet!, withEvent event: UIEvent!) {
myShip.xVelocity = 0
}
Part 4 Update event that changes the Ship's position
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
let rate: CGFloat = 0.5; //Controls rate of motion. 1.0 instantaneous, 0.0 none.
let relativeVelocity: CGVector = CGVector(dx:myShip.xVelocity - myShip.physicsBody.velocity.dx, dy:0);
myShip.physicsBody.velocity = CGVector(dx:myShip.physicsBody.velocity.dx + relativeVelocity.dx*rate, dy:0);
Thanks for reading, and looking forward to a response!
You can save yourself a lot of trouble by using: myShip.physicsBody.applyImpluse(vector). It works by acting as if you gave myShip a push in the direction vector points. If you calculate vector as the x distance from your last touch location to myShip, then it'll accelerate, decelerate, change direction, etc. pretty close to the way you're describing because it'll be giving it little pushes in the right direction on each update.
Basically you store the last touch location then, in your update function, you calculate the CGVector pointing from myShip to lastTouch and apply that as an impulse to your physics body.
Something like:
var lastTouch: CGPoint? = nil
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
let touch = touches.anyObject() as UITouch
let touchLocation = touch.locationInNode(self)
lastTouch = touchLocation
}
override func touchesMoved(touches: NSSet!, withEvent event: UIEvent!) {
let touch = touches.anyObject() as UITouch
let touchLocation = touch.locationInNode(self)
lastTouch = touchLocation
}
// Be sure to clear lastTouch when touches end so that the impulses stop being applies
override func touchesEnded(touches: NSSet!, withEvent event: UIEvent!) {
lastTouch = nil
}
override func update(currentTime: CFTimeInterval) {
// Only add an impulse if there's a lastTouch stored
if let touch = lastTouch {
let impulseVector = CGVector(touch.x - myShip.position.x, 0)
// If myShip starts moving too fast or too slow, you can multiply impulseVector by a constant or clamp its range
myShip.physicsBody.applyImpluse(impulseVector)
}
}
You'll also probably want to play with the linearDamping and angularDamping values on myShip.physicsBody. They'll help determine how fast myShip accelerates and decelerates.
I maxed out the values at 1.0 in my app:
myShip.physicsBody.linearDamping = 1.0
myShip.physicsBody.angularDamping = 1.0
If myShip doesn't stop fast enough for you, you can also try applying some breaking in your update function:
override func update(currentTime: CFTimeInterval) {
// Only add an impulse if there's a lastTouch stored
if let touch = lastTouch {
let impulseVector = CGVector(touch.x - myShip.position.x, 0)
// If myShip starts moving too fast or too slow, you can multiply impulseVector by a constant or clamp its range
myShip.physicsBody.applyImpluse(impulseVector)
} else if !myShip.physicsBody.resting {
// Adjust the -0.5 constant accordingly
let impulseVector = CGVector(myShip.physicsBody.velocity.dx * -0.5, 0)
myShip.physicsBody.applyImpulse(impulseVector)
}
}
For 2017 here's the easy way to do what is explained in the correct answer here.
There's no need to store the previous position, it is given to you...
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
let t: UITouch = touches.first! as UITouch
let l = t.location(in: parent!)
let prev = t.previousLocation(in: parent!)
let delta = (l - prev).vector
physicsBody!.applyImpulse(delta)
}
That's it.
Two notes. (A) properly you should divide the delta distance by the deltaTime to get the correct impulse. If you're a hobbyist really just multiply by "about 100" and you'll be fine. (B) note that of course you will need an extension or function to convert CGPoint to CGVector, it's impossible to do anything without that.
In your thuchesBegan and touchesMoved store the touch location as the "target". In the update then check the position of your ship and reset the xVelocity to 0 if the ship has reached/passed the target.
Since you are only interested in the x coordinate you could also store just touchLocation.x. You can also reverse the velocity but I think that would look strange. Note that if the user moves the finger again, your ship will start moving again because the touchMoved will be triggered again.
On a side note, within touchesMoved you are also setting the shipLeft property but this is not set in your touchesBegan. If this property is used elsewhere you should sync its use.