【iOS】UITabView/UICollectionView 全选问题

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发布时间：2019-06-27

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July. 30th 2016

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Recently in my new project I need to select all the cell data in my UITabViewCell and UICollectionViewCell, and need to do some operations with all the cells(like delete etc.), What I do as follows:

UITabView

private func selectAll(select: Bool) {    let numSections = mListTableView?.numberOfSections    if let numSections = numSections {        for numSection in  0 ..< numSections{            let numItems = mListTableView?.numberOfRowsInSection(numSection)            if let numItems = numItems {                for numItem in 0 ..< numItems {                    selectCell(NSIndexPath(forRow: numItem, inSection: numSection), select: select)                }            }        }    }}private func selectCell(indexPath : NSIndexPath, select: Bool) {    if mListTableView?.cellForRowAtIndexPath(indexPath) != nil {        let cell = mListTableView?.cellForRowAtIndexPath(indexPath) as! DownloadListViewCell        //cell.setSelected(select, animated: true)        cell.setSelectForDelete(select)  // select status UI in UITabViewCell        mDownloadList[indexPath.row].selectToDelete = select  // Pojo data    }}

View Code

UICollectionView

private func selectAll(select: Bool) {    let numSections = mMyOfflineCollectView?.numberOfSections()    if let numSections = numSections {        for numSection in  0 ..< numSections{            let numItems = mMyOfflineCollectView?.numberOfItemsInSection(numSection)            if let numItems = numItems {                for numItem in 0 ..< numItems {                    selectCell(NSIndexPath(forRow: numItem, inSection: numSection), flag: select)                }            }        }    }}private func selectCell(indexPath : NSIndexPath, flag: Bool) {    if mMyOfflineCollectView.cellForItemAtIndexPath(indexPath) != nil {        let cell = mMyOfflineCollectView.cellForItemAtIndexPath(indexPath) as! MyOfflineCollectionViewCell        cell.setSelect(flag)        if flag {            mMyOfflineCollectView.selectItemAtIndexPath(indexPath, animated: true, scrollPosition: UICollectionViewScrollPosition.None)        }else {            mMyOfflineCollectView.deselectItemAtIndexPath(indexPath, animated: true)        }        mMyofflinesData[indexPath.row].needDelete = flag    }}

View Code

But, The problem is , I can only select the visible cell when I scoll down or up, or do operations

Solutions in NetWork

The real problem happened at the cellForRowAtIndexPath / cellForItemAtIndexPath, Which defined in Apple as follows:

public func cellForRowAtIndexPath(indexPath: NSIndexPath) -> UITableViewCell? // returns nil if cell is **not visible** or index path is out of range

public func cellForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewCell?

When the cell is not visible, the cellForRowAtIndexPath will return nil,

So, it’s not the right way to do the cell select operation out the

UITableViewDataSource in cellForRowAtIndexPath (UITabView), you should do it separate. The right way as follows:

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {    let cell = tableView.dequeueReusableCellWithIdentifier(DOWNLOAD_LIST_CELL_INDENTIFIER, forIndexPath: indexPath) as! DownloadListViewCell    cell.selectionStyle = UITableViewCellSelectionStyle.None            // ...     cell.setSelectForDelete(self.mDownloadList[indexPath.row].selectToDelete)// select status UI in UITabViewCell    // ...    return cell}private func selectCell(indexPath : NSIndexPath, select: Bool) {    mDownloadList[indexPath.row].selectToDelete = select // Pojo data    mListTableView?.reloadData() // reloadData}