我正在制作一个基于 Sprite 的游戏。在将物理学应用于我的硬币 Sprite 时,我开始遇到这个错误。关于如何避免它有什么建议吗?
@objc func spawnEnemy(){
enemy = childNode(withName: "enemy") as? SKSpriteNode
coin = childNode(withName: "coin") as? SKSpriteNode
self.physicsWorld.contactDelegate = self
及以后
for coin in sprites{
if coin.name == "coin"{
coin.physicsBody = SKPhysicsBody(rectangleOf: enemy.size)
coin.physicsBody?.categoryBitMask = PhysicsCategory.coin
coin.physicsBody?.contactTestBitMask = PhysicsCategory.player
coin.physicsBody?.affectedByGravity = false
coin.physicsBody?.isDynamic = true
}
}
最佳答案
您应该始终使用“if let”或“guard let”安全地解开可选值
通过使用 if let :
if let coin = coin , let name = coin.name {
// you can use "coin" or "name" safely here
}else{
// "coin" or "name" is nil
}
通过使用guard let:
guard let coin = coin , let name = coin.name else {
// "coin" or "name" is nil
return
}
//you can use "coin" or "name" safely here
关于swift - 解包可选错误时意外发现 nil,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55428447/