如何以longFormHeight进行初始化？

[nattychao]

当我设置了shortFormHeight和longFormHeight，我想初始化的时候以longFormHeight的高度弹起，目前只能先设置shortFormHeight和longFormHeight一样，然后在viewDidAppear里调用panModalSetNeedsLayoutUpdate()去更新shortFormHeight，有点麻烦，需要控制器里保存一个flag用于判断，直接初始化就设定就好了：目前这样
var initFormHeight: PanModalPresentationController.PresentationState {
return PanModalPresentationController.PresentationState.longForm
}