Swift Animation behaves weird after changing Label - ios

Question

I am currently working on an animation for my ios application. When it gets triggered three blocks (UIView with borders) move down and a new block comes in from the left.
It works perfectly until I change the text of the label (Block Number) before the animation starts. The blocks spawn in completely different positions and move back to the start position. They also change their order.
The following code shows my block class. For the animation I use the getBlockView and "view.frame = GCRect(...)". For changing the label text I use the setBlockName(number: String) function.
At the moment I don´t have any idea what could cause that and would be thankful for every suggestion what could cause this weird behaviour.
class myBlock {
var positionID: Int
var blockNumber: String
let blockView: UIView
let blockNumberLabel: UILabel
init(blockNumber: String, heightScreen: CGFloat, widthScreen: CGFloat, positionID: Int) {
self.positionID = positionID
self.blockNumber = blockNumber
blockView = {
let view = UIView()
view.autoSetDimension(.height, toSize: heightScreen / 6)
view.autoSetDimension(.width, toSize: widthScreen - 80)
view.layer.borderWidth = 3
view.layer.borderColor = UIColor.MyTheme.primaryColor1.cgColor
return view
}()
blockNumberLabel = {
let label = UILabel()
label.textColor = UIColor.MyTheme.primaryColor1
label.font = UIFont(name: "ArialMT", size: 20)
label.numberOfLines = 2
label.textAlignment = .left
label.adjustsFontForContentSizeCategory = true
label.text = "Block Number: \(blockNumber)"
label.isUserInteractionEnabled = false
return label
}()
blockView.addSubview(blockNumberLabel)
blockNumberLabel.autoPinEdge(toSuperviewEdge: .top, withInset: 5.0)
blockNumberLabel.autoPinEdge(toSuperviewEdge: .left, withInset: 5.0)
blockNumberLabel.autoPinEdge(toSuperviewEdge: .right, withInset: 5.0)
}
func getBlockView() -> UIView{
return blockView
}
func setBlockName(number: String) {
self.blockNumberLabel.text = "Block Number: \(number)"
}
func getBlockLabel() -> UILabel{
return blockNumberLabel
}
func getID() -> Int {
return positionID
}
func setID(id: Int) {
self.positionID = id
print("\(blockNumberLabel.text!): \(id)")
}
}
Animation Code:
private func moveBlocksDown(blockNumber: String) {
var resetBlock: UIView!
let animationHeight = (self.heightScreen / 6) + (self.blockDistance)
UIView.animate(withDuration: 2.0, animations: {
for var block in self.blockList {
let id = block.getID()
let blockView = block.getBlockView()
if block.getID() == 0 {
block.setBlockName(number: blockNumber)
}
print(id)
switch id {
case 0:
blockView.frame = CGRect(x: self.topX, y: self.topY, width: blockView.frame.width, height: blockView.frame.height)
print(block.getBlockLabel().text!)
case 1:
blockView.frame = CGRect(x: self.topX, y: self.middleY, width: blockView.frame.width, height: blockView.frame.height)
print(block.getBlockLabel().text!)
case 2:
blockView.frame = CGRect(x: self.topX, y: self.bottomY, width: blockView.frame.width, height: blockView.frame.height)
print(block.getBlockLabel().text!)
case 3:
blockView.frame = CGRect(x: self.topX, y: (self.bottomY + animationHeight), width: blockView.frame.width, height: blockView.frame.height)
print(block.getBlockLabel().text!)
resetBlock = blockView
default:
print("Unknown ID")
}
print("NewID \((id + 1) % 4)")
block.setID(id: (id + 1) % 4)
}
}, completion: { finish in
resetBlock.frame = CGRect(x: self.newX, y: self.newY, width: resetBlock.frame.width, height: resetBlock.frame.height)
})
}