swift3.0layer折叠 淘宝商品View折叠

func angle2Radian(offset:Double,ref:Double)->Double {
        return offset * M_PI / ref;
    }

var transfrom:CATransform3D = CATransform3DIdentity
        let d:CGFloat = 300
        transfrom.m34 = -1 / d
        transfrom =  CATransform3DRotate(transfrom,CGFloat(angle2Radian(offset: 30,ref: 200)),1,0)
        view.layer.transform = transfrom