let max = self.sellerArray.max { (model1, model2) -> Bool in return getDateNum(date: model1.lastMsgDate) > getDateNum(date: model2.lastMsgDate)
}//取某个值最大的模型 self.chatArray.append(max!)
self.chatArray = self.chatArray.sorted(by: { (model1,model2) -> Bool in return getDateNum(date: model1.lastMsgDate) > getDateNum(date: model2.lastMsgDate)
})//根据某个值排序
