Swift.jpg

下拉刷新可以說(shuō)是每個(gè)項(xiàng)目的必須品，最近在做一個(gè) Swift 的項(xiàng)目，本著以鍛煉自己的目的，封裝了一個(gè)下拉刷新庫(kù) LCRefresh ，在這里分享給大家。

開(kāi)源庫(kù) LCRefresh 的 Demo 以及源碼已經(jīng)上傳到 Git

https://github.com/liutongchao/LCRefresh

1、如何使用 LCRefresh

使用 LCRefresh 非常方便，只需添加一行代碼。

Pod 支持

pod 'LCRefresh', '~> 0.1.12'

添加下拉刷新 和 上拉加載

import LCRefresh

table.refreshHeader = LCRefreshHeader.init(refreshBlock: {
       print("Header 刷新")
        //TODO
 })

table.refreshFooter = LCRefreshFooter.init(refreshBlock: {
         print("Footer 刷新")
        //TODO
 })

完成刷新

weak var weakSelf = self
if weakSelf!.table.isHeaderRefreshing() {
    weakSelf!.table.endHeaderRefreshing()
}

if weakSelf!.table.isFooterRefreshing() {
    weakSelf!.table.endFooterRefreshing()
}

數(shù)據(jù)加載完畢

weakSelf!.table.setDataLoadover()

weakSelf!.table.resetDataLoad()

刷新的效果圖

HeaderRefresh.png

2、如何去封裝自己的刷新控件

這里分享一下封裝刷新控件的心路歷程

① 創(chuàng)建刷新視圖，并創(chuàng)建View的各種狀態(tài)(因?yàn)橐С謕od xib改為了純代碼)

LCRefreshHeader

extension LCRefreshHeader{
/** 各種狀態(tài)切換 */
func setNomalStatus() {
    if activity.isAnimating {
        activity.stopAnimating()
    }
    activity.isHidden = true
    
    contenLab.text = "下拉可以刷新"
    image.isHidden = false
    
    UIView.animate(withDuration: 0.2, animations: {
        self.image.transform = CGAffineTransform.identity
    })
}

func setWaitRefreshStatus() {
    if activity.isAnimating {
        activity.stopAnimating()
    }
    activity.isHidden = true
    
    contenLab.text = "松開(kāi)立即刷新"
    image.isHidden = false
    
    UIView.animate(withDuration: 0.2, animations: {
        self.image.transform = CGAffineTransform(rotationAngle: CGFloat(-M_PI))
        
    })
}

func setRefreshingStatus() {
    activity.isHidden = false
    activity.startAnimating()
    
    contenLab.text = "正在刷新數(shù)據(jù)..."
    image.isHidden = true
}

}

②拓展 UIScrollView 動(dòng)態(tài)綁定屬性

 /** header **/
public var refreshHeader: LCRefreshHeader? {
    get{
        let key = UnsafeRawPointer.init(bitPattern: "refreshHeader".hashValue)
        let result = objc_getAssociatedObject(self, key) as? LCRefreshHeader
        return result
    }
    set{
        let key = UnsafeRawPointer.init(bitPattern: "refreshHeader".hashValue)
        objc_setAssociatedObject(self, key, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
        
        let result = objc_getAssociatedObject(self, key) as? LCRefreshHeader
        if result != nil {
            self.addSubview(result!)
        }
        //添加滑動(dòng)監(jiān)測(cè)
        addOffsetObserver()
        weak var weakSelf = self
        weakSelf!.panGestureRecognizer.addTarget(weakSelf!, action: #selector(UIScrollView.scrollViewDragging(_:)))
    }
    
}
/** footer **/
public var refreshFooter: LCRefreshFooter? {
    get{
        let key = UnsafeRawPointer.init(bitPattern: "refreshFooter".hashValue)
        let result = objc_getAssociatedObject(self, key) as? LCRefreshFooter
        return result
    }
    set{
        let key = UnsafeRawPointer.init(bitPattern: "refreshFooter".hashValue)
        objc_setAssociatedObject(self, key, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
        
        let result = objc_getAssociatedObject(self, key) as? LCRefreshFooter
        if result != nil {
            result!.isHidden = true
            self.addSubview(result!)
        }
        //添加滑動(dòng)監(jiān)測(cè)
        addOffsetObserver()
        weak var weakSelf = self
        weakSelf!.panGestureRecognizer.addTarget(weakSelf!, action: #selector(UIScrollView.scrollViewDragging(_:)))
    }
    
}

添加視圖，監(jiān)測(cè) ScrollView 滑動(dòng)，以及drag 響應(yīng)

③根據(jù)ScrollView的 contentOffset 來(lái)區(qū)分是下拉刷新還是上拉加載，然后根據(jù) contentOffset 的值來(lái)切換刷新View的狀態(tài)

/** 滑動(dòng)相關(guān) */

 open override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "contentOffset" {
        let offSet = self.contentOffset.y
        let scrollHeight = self.bounds.size.height
        let inset = self.contentInset
        var currentOffset = offSet + scrollHeight - inset.bottom
        let maximumOffset = self.contentSize.height
        
        /** 數(shù)據(jù)未充滿屏幕的情況 **/
        if maximumOffset < scrollHeight {
            currentOffset = offSet + maximumOffset - inset.bottom
        }
        
        if offSet < 0 {
            /** 下拉刷新 */
            guard self.refreshHeader != nil else{
                return
            }
            scrollHeader(offSet)
            self.refreshObj = LCRefreshObject.header
            
            
        }else if currentOffset - maximumOffset > 0 {
            /** 上拉刷新 */
            
            guard self.refreshFooter != nil else{
                return
            }
            guard self.refreshFooter!.refreshStatus != .loadover else {
                return
            }

            scrollFooter(currentOffset - maximumOffset)
            self.refreshObj = .footer
            
        }else{
            /** 無(wú)刷新對(duì)象 */
            self.refreshObj = .none
        }

    }
}

View狀態(tài)切換

 func scrollHeader(_ offSet: CGFloat) {//參數(shù)為負(fù)數(shù)
    guard self.refreshHeader != nil else{
        print("Header加載失敗")
        return
    }
    guard self.refreshHeader!.refreshStatus != .refreshing else{
        return
    }
    if offSet < -LCRefreshHeaderHeight {
        self.refreshHeader!.setStatus(LCRefreshHeaderStatus.waitRefresh)
    }else{
        self.refreshHeader!.setStatus(LCRefreshHeaderStatus.normal)
    }

}

④最后拖拽結(jié)束時(shí)再根據(jù)刷新對(duì)象切換View 到刷新?tīng)顟B(tài)。

/** 拖拽相關(guān) */
func scrollViewDragging(_ pan: UIPanGestureRecognizer){
    if pan.state == .ended{
        if self.refreshObj == LCRefreshObject.header {
            draggHeader()

        }else if self.refreshObj == LCRefreshObject.footer{
            draggFooter()
        }
    }
}

這之間涉及到contentOffset值的設(shè)置，在這里就不一一明說(shuō)了，給出的源碼里都有。

現(xiàn)在只是開(kāi)發(fā)出了這一種樣式，以后會(huì)更多的樣式以供大家使用，當(dāng)然，你也可以根據(jù)給出的源碼自己來(lái)修改樣式。

有好的建議歡迎來(lái)與我互相探討 -- LC.West