Determine only one contact SpriteKit - swift

Question

The main question is: How to determine only one contact?
part of code:
extension GameScene : SKPhysicsContactDelegate {
func didBegin(_ contact: SKPhysicsContact) {
let bodyA = contact.bodyA.categoryBitMask
let bodyB = contact.bodyB.categoryBitMask
let ball = BitmaskCategory.ball
let bucket = BitmaskCategory.bucket
if bodyA == ball && bodyB == bucket || bodyA == bucket && bodyB == ball {
print("contact")
// block.run(SKAction.repeatForever(blockInstanse.rotateBlock(block: block)))
}
}}
When I put ball in bucket, i have that output because ball has bouncing effect.
Want to write some logic in that func but I can't because have several contacts.
Tried to change ball.physicsBody?.categoryBitMask in "if" condition but without success too.
Please help...

Answer 1

Your ball or bucket can set a flag on the first contact, you can check inside the didBegin and run action if is true, like:
var isFirstContact = true
func didBegin(_ contact: SKPhysicsContact) {
let bodyA = contact.bodyA.categoryBitMask
let bodyB = contact.bodyB.categoryBitMask
let ball = BitmaskCategory.ball
let bucket = BitmaskCategory.bucket
if bodyA == ball && bodyB == bucket || bodyA == bucket && bodyB == ball {
if isFirstContact {
isFirstContact = false
// block.run(SKAction.repeatForever(blockInstanse.rotateBlock(block: block)))
}
}
}}