Question

我有一个tableViewController，它有4个单元格。每个单元格都是从viewDidLoad（）中的xib文件加载的：

override func viewDidLoad() {
    super.viewDidLoad()
    let itemPreBasketServer = ItemPreBasketServer()
    let searchForIDServer = SearchForIDServer()

    let descCell = UINib(nibName: "PreDescTableViewCell", bundle: nil)
    tableView.register(descCell, forCellReuseIdentifier: "descCell")

    let priceCell = UINib(nibName: "PrePriceTableViewCell", bundle: nil)
    tableView.register(priceCell, forCellReuseIdentifier: "priceCell")

    let quantityCell = UINib(nibName: "PreQuantityTableViewCell", bundle: nil)
    tableView.register(quantityCell, forCellReuseIdentifier: "quantityCell")

    let submitCell = UINib(nibName: "PreSubmitTableViewCell", bundle: nil)
    tableView.register(submitCell, forCellReuseIdentifier: "submitCell")

    if incomeName != "" {
        characterSet.insert(charactersIn: "=\"#%/<>?@\\^`{|}&")
        incomeType = incomeType.replacingOccurrences(of: "&", with: "%26")
        incomeType = incomeType.replacingOccurrences(of: "'", with: "%27")
        incomeName = incomeName.replacingOccurrences(of: "&", with: "%26")
        incomeName = incomeName.replacingOccurrences(of: "'", with: "%27")
        searchForIDServer.name = incomeName.addingPercentEncoding(withAllowedCharacters: characterSet)!
        searchForIDServer.type = incomeType.addingPercentEncoding(withAllowedCharacters: characterSet)!
        searchForIDServer.delegate = self
        searchForIDServer.downloadItems()
    } else {
        searchForIDServer.name = incomeName.addingPercentEncoding(withAllowedCharacters: characterSet)!
        itemPreBasketServer.id = String(incomeID)
        itemPreBasketServer.delegate = self
        itemPreBasketServer.downloadItems()
    }
}

我还有一个名为cellItems的数组，它由searchForIDServer.downloaditems（）或itemPreBaskeyServer.downloaditems（）中的协议填充：

var cellItems: NSArray = NSArray() {
    didSet {
        tableView.reloadData()
    }
}

    func itemsDownloaded(items: NSArray) {
    cellItems = items
    tableView.reloadData()
}

现在问题是，在我的cellForRowAt函数中，当我在cellItems上创建一个var时，我得到一个错误：

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let item: ItemPreBasketModel = cellItems[indexPath.row] as! ItemPreBasketModel
    if indexPath.section == 0 && indexPath.row == 0 {

        //This will be the desc
        let descCell: PreDescTableViewCell = tableView.dequeueReusableCell(withIdentifier: "descCell", for: indexPath)as! PreDescTableViewCell
        print(item.name)
        return descCell
    } else if indexPath.section == 0 && indexPath.row == 1 {
        //This will be the price
        let priceCell: PrePriceTableViewCell = tableView.dequeueReusableCell(withIdentifier: "priceCell", for: indexPath)as! PrePriceTableViewCell
        return priceCell
    } else if indexPath.section == 0 && indexPath.row == 2 {
        //This will be the quantity
        let quantityCell: PreQuantityTableViewCell = tableView.dequeueReusableCell(withIdentifier: "quantityCell", for: indexPath)as! PreQuantityTableViewCell
        return quantityCell
    } else {
        //Submit
        let submitCell: PreSubmitTableViewCell = tableView.dequeueReusableCell(withIdentifier: "submitCell", for: indexPath)as! PreSubmitTableViewCell
        return submitCell
    }
}

我在运行时得到的错误是：

    2018-01-31 16:41:28.884725+0000 SpiceCentral[5487:468249] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArray0 objectAtIndex:]: index 0 beyond bounds for empty NSArray'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000102a0912b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x0000000101b50f41 objc_exception_throw + 48
    2   CoreFoundation                      0x0000000102a21ebd -[__NSArray0 objectAtIndex:] + 93
    3   SpiceCentral                        0x00000001011ba494 _T012SpiceCentral32ItemPreBasketTableViewControllerC05tableG0So07UITableG4CellCSo0jG0C_10Foundation9IndexPathV12cellForRowAttF + 132
    4   SpiceCentral                        0x00000001011bb0dc _T012SpiceCentral32ItemPreBasketTableViewControllerC05tableG0So07UITableG4CellCSo0jG0C_10Foundation9IndexPathV12cellForRowAttFTo + 92
    5   UIKit                               0x0000000103521484 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 778
    6   UIKit                               0x0000000103521a2a -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 74
    7   UIKit                               0x00000001034e71f6 -[UITableView _updateVisibleCellsNow:isRecursive:] + 3031
    8   UIKit                               0x00000001035092e6 -[UITableView layoutSubviews] + 176
    9   UIKit                               0x0000000103491a6d -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1439
    10  QuartzCore                          0x000000010c45f61c -[CALayer layoutSublayers] + 159
    11  QuartzCore                          0x000000010c4637ad _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 401
    12  QuartzCore                          0x000000010c3ea86c _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 364
    13  QuartzCore                          0x000000010c417946 _ZN2CA11Transaction6commitEv + 500
    14  UIKit                               0x00000001033ea167 _afterCACommitHandler + 272
    15  CoreFoundation                      0x00000001029abc07 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    16  CoreFoundation                      0x00000001029abb5e __CFRunLoopDoObservers + 430
    17  CoreFoundation                      0x0000000102990124 __CFRunLoopRun + 1572
    18  CoreFoundation                      0x000000010298f889 CFRunLoopRunSpecific + 409
    19  GraphicsServices                    0x0000000108e869c6 GSEventRunModal + 62
    20  UIKit                               0x00000001033c05d6 UIApplicationMain + 159
    21  SpiceCentral                        0x00000001011c1ec7 main + 55
    22  libdyld.dylib                       0x000000010749bd81 start + 1
    23  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

我已经尽力解决这个问题，但没有运气。我在其他视图控制器中以完全相同的方式填充其他tableviews，唯一不同的是我预先将我的单元格数定义为4，并且我在ViewDidLoad中也使用了一些逻辑。我基本上是在说“嘿viewController，如果你还没有ID，请通过运行这个函数来获取它，这将填充我的cellItems，否则如果你有ID，运行这个函数。

Answer 1

你是什么意思＆＃34;预先定义我的细胞计数为4＆＃34;？如果您定义以下方法：

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 4
}

然后它看起来合乎逻辑，你得到一个错误。最开始cellItems数组为空，但cellForRowAt方法将被调用，因为numberOfRowsInSection为4. cellItems[indexPath.row]将引发错误，因为数组为空

Answer 2

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) ->

 Int {
        if( cellItems?.count < 4 ) return 0
        return 4
        /* Note: If cellItems will always have 4 items when it's loaded, the following line would be appropriate on its own: */
        // return cellItems?.count
 }

CellForRowAt函数在访问每行上的数组时抛出错误？

2 个答案: