skfieldnode isexclusive设置为true，但仍不排斥

Question

这是我的代码：

func backgroundandfield(withTexture: SKTexture) {
        let background = SKSpriteNode(color: .clear, size: CGSize(width: 6000, height: 1000))
        background.zPosition = -1000
        background.position.y = -500
        background.position.x = 2500
        background.size = CGSize(width: 6000, height: 1000)
        self.addChild(background)

    let field = SKFieldNode.linearGravityField(withVector: vector3(0, 1, 0))
    field.region = SKRegion(size: background.size)
    field.position = background.position
    field.categoryBitMask = 1
    field.isEnabled = true
    field.isExclusive = true
    field.falloff = 0.4
    field.strength = 25
    field.name = "field"
    self.addChild(field)
}

func initgravity() {
        let gfield = SKFieldNode.linearGravityField(withVector: vector3(0, -2, 0))
        gfield.isEnabled = true
        gfield.isExclusive = false
        gfield.strength = 7

        self.addChild(gfield)
    }

这两个函数均在didmove中调用。我的问题是，播放器节点在另一个字段中时仍被“ gfield”下拉。为什么我的.isExculsive无法正常工作？