一行代码搞定下拉刷新和无数据时空白图

下拉刷新依然使用MJRefresh，为了不每一次下拉刷新都写两个方法且重复的数据处理逻辑，给UIScrollView添加一个分类，使用运行时绑定pageNo和pageSize，废话不多说直接上代码

import UIKit
import MJRefresh

extension UIScrollView {
    struct runtimeKey {
        static var pageNoKey = UnsafeRawPointer.init(bitPattern: "pageNoKey".hashValue)
        static var pageSizeKey = UnsafeRawPointer.init(bitPattern: "pageSizeKey".hashValue)
        static var dataSourceKey = UnsafeRawPointer.init(bitPattern: "dataSourceKey".hashValue)

    }

    var pageNo:Int? {
        set{
            objc_setAssociatedObject(self, UIScrollView.runtimeKey.pageNoKey!, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_ASSIGN)
        }
        get {
            return  objc_getAssociatedObject(self, UIScrollView.runtimeKey.pageNoKey!) as? Int
        }
    }
    var pageSize:Int? {
        set{
            objc_setAssociatedObject(self, UIScrollView.runtimeKey.pageSizeKey!, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_ASSIGN)
        }
        get {
            return  objc_getAssociatedObject(self, UIScrollView.runtimeKey.pageSizeKey!) as? Int
        }
    }
    
    var refreshDataSource:Array<Any>? {
        set{
            objc_setAssociatedObject(self, UIScrollView.runtimeKey.dataSourceKey!, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
        }
        get {
            return  objc_getAssociatedObject(self, UIScrollView.runtimeKey.dataSourceKey!) as? Array
        }
    }

    

    
    var uHead: MJRefreshHeader {
        get { return (mj_header ?? MJRefreshHeader.init())! }
        set { mj_header = newValue }
    }
    
    var uFoot: MJRefreshFooter {
        get { return (mj_footer ?? MJRefreshFooter.init())! }
        set { mj_footer = newValue }
    }
    
    func lf_addHeader(beginRefresh:Bool, block:@escaping LFCallBack){
        self.pageSize = 10
        self.pageNo = 1

        self.uHead = URefreshHeader{[unowned self] in
            self.pageNo = 1

            block()
        }
        if beginRefresh {
            self.uHead.beginRefreshing()
        }
    }
    func lf_addFooter(block:@escaping LFCallBack){
        self.uFoot = URefreshFooter{[unowned self] in
            self.pageNo! += 1
            block()
        }
    }
    
    func lf_setRefresh(dataSource:Array<Any>?){
        if self.pageNo == 1 {
            self.refreshDataSource = dataSource
            
        }else {
            self.refreshDataSource? += dataSource ?? []
        }
        
        if self.refreshDataSource?.count == 0 {
            self.ly_showEmpty()
        }else {
            self.ly_hideEmpty()
        }
        
        self.uHead.endRefreshing()
        if dataSource?.count == 0 && dataSource?.count ?? 0 < self.pageSize ?? 10 {
            self.uFoot.endRefreshingWithNoMoreData()
        }else {
            self.uFoot.endRefreshing()
        }
    }
}

class URefreshHeader: MJRefreshGifHeader {
    override func prepare() {
        super.prepare()
        lastUpdatedTimeLabel?.isHidden = true
        stateLabel?.isHidden = true
    }
}

class URefreshAutoHeader: MJRefreshHeader {}

class URefreshFooter: MJRefreshBackNormalFooter {}

class URefreshAutoFooter: MJRefreshAutoFooter {}


class URefreshDiscoverFooter: MJRefreshBackGifFooter {
    
    override func prepare() {
        super.prepare()
//        backgroundColor = UIColor.init(red: 239/255.0, green: 239/255.0, blue: 239/255.0, alpha: 1)
        backgroundColor = UIColor.clear
        setImages([UIImage(named: "pullToRefresh_0_80x60_")!], for: .idle)
        stateLabel?.isHidden = true
        refreshingBlock = { self.endRefreshing() }
    }
}

class URefreshTipKissFooter: MJRefreshBackFooter {
    
    lazy var tipLabel: UILabel = {
        let tl = UILabel()
        tl.textAlignment = .center
        tl.textColor = UIColor.lightGray
        tl.font = UIFont.systemFont(ofSize: 14)
        tl.numberOfLines = 0
        return tl
    }()
    
    lazy var imageView: UIImageView = {
        let iw = UIImageView()
        iw.image = UIImage(named: "pullToRefresh_0_80x60_")
        return iw
    }()
    
    override func prepare() {
        super.prepare()
//        backgroundColor = UIColor.init(red: 239/255.0, green: 239/255.0, blue: 239/255.0, alpha: 1)
        backgroundColor = UIColor.clear
        mj_h = 240
        addSubview(tipLabel)
        addSubview(imageView)
    }
    
    override func placeSubviews() {
        tipLabel.frame = CGRect(x: 0, y: 40, width: bounds.width, height: 60)
        imageView.frame = CGRect(x: (bounds.width - 80 ) / 2, y: 110, width: 80, height: 80)
    }
    
    convenience init(with tip: String) {
        self.init()
        refreshingBlock = { self.endRefreshing() }
        tipLabel.text = tip
    }
}

以上核心代码主要看lf_setRefresh这个方法，包含了数据源处理和空白图的处理
具体使用方法：在控制器中添加两行

        tableView.lf_addHeader(beginRefresh: true) {[unowned self] in
            self.loadData()
        }
        tableView.lf_addFooter {[unowned self] in
            self.loadData()
        }

还没完，需要在loadData方法设置一下数据源，调用lf_setRefresh方法

    func loadData() {
        HttpRequest.loadData(target: PXSArticleAPI.articleList(page: tableView.pageNo ?? 1, cate: self.cateId ?? 0,title:searchStr ?? ""), success: { (res) in
                let json = JSON(res)
                let article_list = JSONDeserializer<PXSArticleListModel>.deserializeModelArrayFrom(json: json["data"]["result"]["article_list"].description)
                
//            self.mdataSource = article_list as! Array<PXSArticleListModel>
            self.tableView.lf_setRefresh(dataSource: article_list as?[PXSArticleListModel])
            self.tableView.reloadData()

        }) { (state_code, message) in
            self.tableView.uHead.endRefreshing()
            self.tableView.uFoot.endRefreshing()
        }
    }

到这里所以逻辑都完成了，执行给tableView设置数据源的时候通过self.tableView.refreshDataSource?.count获取处理后的数据源

    override func numberOfSections(in tableView: UITableView) -> Int {
        return self.tableView.refreshDataSource?.count ?? 0
    }

写的不好勿喷