blocks|key|3223912|text|当您在代码中创建视图时，它的IBOutlet属性不能正确地连接起来。你想要从dequeueReusableCellWithIdentifier得到的版本|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3223913|let+cell+=+tableView.dequeueReusableCellWithIdentifier("BookCell")+as+BookTableViewCell|code-block|syntax|javascript|3223914|entityMap^0|E|8|12|X|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

When you create a view in code, its <code>IBOutlet</code> properties don't get hooked up properly. You want the version that you get back from <code>dequeueReusableCellWithIdentifier</code>:

<pre><code>let cell = tableView.dequeueReusableCellWithIdentifier("BookCell") as BookTableViewCell
</code></pre>

blocks|key|3223920|text|如果您使用的是故事板，请确保在文件开始时没有这一行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3223921|self.tableView.registerClass(CustomTableViewCell.self,+forCellReuseIdentifier:+"customCell")|code-block|syntax|javascript|3223922|它将覆盖故事板，从而忽略故事板中的出口链接。|3223923|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you're using storyboard, make sure you don't have this line at the start of your file:

<pre><code>self.tableView.registerClass(CustomTableViewCell.self, forCellReuseIdentifier: "customCell")
</code></pre>

It will overwrite the storyboard and as a result, the outlet links in the storyboard are ignored.

blocks|key|2922272|text|我收到这个错误是因为我没有在自定义单元格的童话板中写入标识符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2922273|​|2922274|📷|atomic|offset|length|2922275|2922276|还请确保它与以下代码相匹配：|2922277|func+tableView(tableView:+UITableView,+cellForRowAtIndexPath+indexPath:+NSIndexPath)+->+UITableViewCell
++++{

++++++++let+cell+=+tableView.dequeueReusableCellWithIdentifier("CustomTableCell")+as+CustomTableCell

++++++++...
++++}|code-block|syntax|javascript|2922278|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/04e0333b0b4f67c0ce396b2b24220feb.png|imageAlt^0|0|0|0|1|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|11|8|@]|9|@$G|12|H|13|1|14]]|A|$]]|$1|I|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|16|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|17|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X|Y|-4]]]]

I was getting this error because I didn't have the identifier written in the Storyboard of the Custom Cell. 

<img src="https://i.stack.imgur.com/H4GQT.png" alt="StoryBoard">

Also make sure it matches you code in:

<pre><code>func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -&gt; UITableViewCell
 {

 let cell = tableView.dequeueReusableCellWithIdentifier("CustomTableCell") as CustomTableCell

 ...
 }
</code></pre>

blocks|key|2922297|text|可能您在Main.Storyboard中的视图在ViewController文件中丢失了它的IBOutlet引用，只需再次链接它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2922298|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Possibly that your view in Main.Storyboard lost its IBOutlet reference in ViewController file, just link it again.

blocks|key|3612190|text|在我的例子中，这是打开可选选项的方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3612191|let+cellId:String+=+"ConverterTableCell"
let+cell:+ConverterTableViewCell+=+(tableView.dequeueReusableCellWithIdentifier(cellId)!+as?+ConverterTableViewCell)!|code-block|syntax|javascript|3612192|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In my case it was the way the Optional is unwrapped:

<pre><code>let cellId:String = "ConverterTableCell"
let cell: ConverterTableViewCell = (tableView.dequeueReusableCellWithIdentifier(cellId)! as? ConverterTableViewCell)!
</code></pre>

blocks|key|3612194|text|尝试这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3612195|let+cell+=+tableView.dequeueReusableCellWithIdentifier("BookCell",+forIndexPath:+indexPath)+as!+BookTableViewCell|code-block|syntax|javascript|3612196|不要忘记在故事板中设置重用标识符。|3612197|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Try doing this:

<pre><code>let cell = tableView.dequeueReusableCellWithIdentifier("BookCell", forIndexPath: indexPath) as! BookTableViewCell
</code></pre>

and don't forget to set the reuse identifier in your storyboard

blocks|key|3224031|text|每当我使用重用标识符名称不同于自定义类名+unifid这些名称为我解决时，我就会收到这个错误。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3224032|entityMap^0|5|5|F|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

I am getting this error whenever I use reuse Identifer name different than the custom class name
unifid those names solve it for me

blocks|key|3612254|text|不要忘记注册nib+(用Swift3进行测试)，例如，内部覆盖viewDidLoad()：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3612255|self.tableView.register(UINib(nibName:+"BookTableViewCell",+bundle:+nil),+forCellReuseIdentifier:+"BookCell")|code-block|syntax|javascript|3612256|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Do not forget to register nib (tested with Swift3), e. g. inside override func viewDidLoad(): 

<pre><code>self.tableView.register(UINib(nibName: "BookTableViewCell", bundle: nil), forCellReuseIdentifier: "BookCell")
</code></pre>

blocks|key|2922359|text|如果我将UITapGestureRecognizer放在故事板上的自定义UITableViewCell中，就会遇到这个错误。(Xcode版本为8.3)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2922360|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I encounter this error, if I put UITapGestureRecognizer in a custom UITableViewCell on the storyboard.(Xcode version is 8.3).

blocks|key|3224159|text|这个问题之所以会被问到很多，是因为它取决于您如何设置表视图和自定义CellClass。您是以故事板还是以编程方式创建您的表视图？是否创建自定义.xib单元格和自定义单元格类？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3224160|如果您以编程方式创建了表视图并创建了自定义.xib和单元格类，下面是Swift+4的答案|offset|length|style|BOLD|3224161|in+viewDidLoad:

++++++++customTable.register(UINib(nibName:+"NibName",+bundle:+nil),+forCellReuseIdentifier:+"NibNameIdentifier")

in+cellforRowat:
++++++++let+cell+=+tableView.dequeueReusableCell(withIdentifier:+"NibName")+as!+ClassName|code-block|syntax|javascript|3224162|注意:单元格.xib文件中的确保在属性检查器("NibNameIdentifier")中设置标识符。|3224163|entityMap^0|0|Y|7|0|0|0|E|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|U|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|V|8|@$D|W|E|X|F|G]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

The reason why this question gets asked a lot is because it depends on how you setup your tableview and custom CellClass. Do you create your tableview in storyboard or programmatically? Do you create custom .xib Cells and custom Cell classes? 

If you created your tableview programmatically and created custom .xib and Cell class here is the answer for Swift 4:

<pre><code>in viewDidLoad:

 customTable.register(UINib(nibName: "NibName", bundle: nil), forCellReuseIdentifier: "NibNameIdentifier")

in cellforRowat:
 let cell = tableView.dequeueReusableCell(withIdentifier: "NibName") as! ClassName
</code></pre>

Note: In your cell .xib file make sure you set your identifier in the Attributes inspector ("NibNameIdentifier").

blocks|key|3612379|text|中的Swift+5|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3612380|首先，我尝试使用下面提到的类和标识符在viewdidload()中注册我的UITableViewCell，但是它对我没有作用。|3612381|self.tableView.registerClass(MyCustomTableViewCell.self,+forCellReuseIdentifier:+"customCell")|code-block|syntax|javascript|3612382|解决方案|3612383|Then+I+registered+my+UITableViewCell+using+Nib+name+and+it+worked+for+me|3612384|使用Nib名称在viewdidload()中注册单元格|3612385|override+func+viewDidLoad()+
{
++++super.viewDidLoad()
++++//+Do+any+additional+setup+after+loading+the+view.

++++//register+your+table+view+cell+in+Viewdidload()+using+Nib+Name+++++++
++++tableView.register(UINib.init(nibName:+"MyCustomTableViewCell",+bundle:+nil),+forCellReuseIdentifier:+"customCell")
}|3612386|entityMap^0|0|9|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|13|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|U|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|V|$]]

In Swift 5

First I tried registering my UITableViewCell in viewdidload() using class and identifier which I have mentioned below but it did not work for me.

<pre><code>self.tableView.registerClass(MyCustomTableViewCell.self, forCellReuseIdentifier: "customCell")
</code></pre>

Solution

<pre><code>Then I registered my UITableViewCell using Nib name and it worked for me
</code></pre>

Register your cell in viewdidload() using Nib name 

<pre><code>override func viewDidLoad() 
{
 super.viewDidLoad()
 // Do any additional setup after loading the view.

 //register your table view cell in Viewdidload() using Nib Name 
 tableView.register(UINib.init(nibName: "MyCustomTableViewCell", bundle: nil), forCellReuseIdentifier: "customCell")
}
</code></pre>

blocks|key|2922430|text|你需要检查两件事|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2922431|1.在viewDidLoad中使用nib名称注册单元格|2922432|2922433|func+viewDidLoad()+
{
++++super.viewDidLoad()
++++listTableView.register(UINib.init(nibName:+"ListProductCell",+bundle:+nil),+forCellReuseIdentifier:+"ListProductCell")
+}|code-block|syntax|javascript|2922434|2.用这种方式创建自定义单元格。|2922435|func+tableView(_+tableView:+UITableView,+cellForRowAt+indexPath:+IndexPath)+->+UITableViewCell+{
++++++++let+cell+=+tableView.dequeueReusableCell(withIdentifier:+"ListProductCell")+as!+ListProductCell
++++++++return+cell
++++}|2922436|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|R|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|S|8|@]|9|@]|A|$H|I]]|$1|J|3|K|5|6|7|T|8|@]|9|@]|A|$]]|$1|L|3|M|5|G|7|U|8|@]|9|@]|A|$H|I]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

You need to check two things

<h2>1. Register cell with nib name in viewDidLoad</h2>

<hr>

<pre><code>func viewDidLoad() 
{
 super.viewDidLoad()
 listTableView.register(UINib.init(nibName: "ListProductCell", bundle: nil), forCellReuseIdentifier: "ListProductCell")
 }
</code></pre>

<h2>2. Create custom cell this way.</h2>

<pre><code>func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -&gt; UITableViewCell {
 let cell = tableView.dequeueReusableCell(withIdentifier: "ListProductCell") as! ListProductCell
 return cell
 }
</code></pre>

blocks|key|2922453|text|Swift+5在同一个故事板中有A类和B类，B类包含表视图插座，当我试图将A类推到B类时，它崩溃了，显示tableview出口为零。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2922454|在A班，我像下面的代码那样进行导航。|2922455|let+classBObj+=+ClassB()
self.navigationController?.pushViewController(classBObj,+animated:+true)|code-block|syntax|javascript|2922456|然后，我意识到我的错误，并使用下面的代码，这是完美的工作。|2922457|let+storyboard+=+UIStoryboard(name:+"Main",+bundle:+nil)
let+classBObj+=+storyboard.instantiateViewController(withIdentifier:+"ClassB")+as!+ClassB
self.navigationController?.pushViewController(classBObj,+animated:+true)|2922458|entityMap^0|0|7|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|R|$]]

Swift 5
In same storyboard two class are there Class A and Class B, Class B contains tableview outlet, when i tried to push Class A to Class B it's crashed and show tableView outlet nil. 

In class A i did navigation like below code.

<pre><code>let classBObj = ClassB()
self.navigationController?.pushViewController(classBObj, animated: true)
</code></pre>

Then i realised my mistake and used below code and it's work perfectly.

<pre><code>let storyboard = UIStoryboard(name: "Main", bundle: nil)
let classBObj = storyboard.instantiateViewController(withIdentifier: "ClassB") as! ClassB
self.navigationController?.pushViewController(classBObj, animated: true)
</code></pre>

Pretty simple code:

<pre><code>func numberOfSectionsInTableView(tableView: UITableView?) -&gt; Int {
 return 1
}

func tableView(tableView:UITableView!, numberOfRowsInSection section:Int) -&gt; Int {
 return 5
}


func tableView(tableView:UITableView!, cellForRowAtIndexPath indexPath:NSIndexPath!) -&gt; UITableViewCell! {
 let cell: BookTableViewCell = BookTableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: "BookCell")
 println("ip: \(indexPath.row)")
 cell.bookLabel.text = "test"

 return cell
}
</code></pre>

On the cell.bookLabel.text line I get this:

<pre><code>fatal error: unexpectedly found nil while unwrapping an Optional value
</code></pre>

The BookTableViewCell is defined like this:

<pre><code>class BookTableViewCell: UITableViewCell {

 @IBOutlet var bookLabel: UILabel

 override func awakeFromNib() {
 super.awakeFromNib()
 // Initialization code
 }

 override func setSelected(selected: Bool, animated: Bool) {
 super.setSelected(selected, animated: animated)

 // Configure the view for the selected state
 }

}
</code></pre>

And bookLabel is correctly hooked up in a Prototype cell in the Storyboard. Why am I getting this error?

Simple UITableView in Swift - unexpectedly found nil

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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非常简单的代码：func numberOfSectionsInTableView(tableView: UITableView?) -> Int {    return 1}func tableView(tableView:UITableView!, numberOfRowsInSection section:Int)...

问Swift中的简单UITableView -意外发现零
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问Swift中的简单UITableView -意外发现零EN