Question

修改

添加异常断点后（感谢Daniel T），我发现它是我的

cell.askingUsernameLabel.text = NSString(string: arr[indexPath.row])

返回nil。

这个问题的解决方案是在swift中，注册Sub类会覆盖你在Storyboards中所做的事情（如果使用storyboard）。只需删除

self.collectionView.registerClass(CollectionViewCell.self, forCellWithReuseIdentifier:"CollectionViewCell")

你很高兴

ORIGINAL

我真的迷失了这个：我试图从我的ViewController在UIView中设置一个UICollectionView。（故事板）

我在几个教程/代码示例之后进行了设置，但是我无法找到为什么我最终总是会遇到＆＃34;致命错误：在解开一个Optional值＆＃34时意外地发现了nil。

这是代码。

控制器层次结构：

View Controller (class:ViewController.swift)
-- UIView 1
-- UIView 2
----- UICollectionView
---------- UICollectionViewCell (class:CollectionViewCell.swift) (dataSource & delegate linked to View Contorller)
--------------- Label

ViewController.swift

class ViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {

    var arr:[String] = []

    @IBOutlet weak var collectionView: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()

        arr = ["title1", "title2"]

        self.collectionView.registerClass(CollectionViewCell.self, forCellWithReuseIdentifier:"CollectionViewCell")

    }

    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        return 1
    }

    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return arr.count
    }

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath) as CollectionViewCell
        cell.askingUsernameLabel.text = arr[indexPath.row]
        return cell
    } 

}

CollectionViewCell

import UIKit

class CollectionViewCell: UICollectionViewCell {

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    @IBOutlet weak var askingUsernameLabel: UILabel!

    override init(frame: CGRect) {
        super.init(frame: frame)
    }
}

我最终遇到这个致命的错误我做错了什么？

there`@objc there.ViewController.collectionView (there.ViewController)(ObjectiveC.UICollectionView, cellForItemAtIndexPath : ObjectiveC.NSIndexPath) -> ObjectiveC.UICollectionViewCell at ViewController.swift:
0xb08c0:  pushl  %ebp
0xb08c1:  movl   %esp, %ebp
0xb08c3:  pushl  %esi
0xb08c4:  subl   $0x24, %esp
0xb08c7:  movl   0x14(%ebp), %eax
0xb08ca:  movl   0x10(%ebp), %ecx
0xb08cd:  movl   0x8(%ebp), %edx
0xb08d0:  movl   %ecx, (%esp)
0xb08d3:  movl   %ecx, -0x8(%ebp)
0xb08d6:  movl   %edx, -0xc(%ebp)
0xb08d9:  movl   %eax, -0x10(%ebp)
0xb08dc:  calll  0x13f0e0                  ; symbol stub for: objc_retain
0xb08e1:  movl   -0x10(%ebp), %ecx
0xb08e4:  movl   %ecx, (%esp)
0xb08e7:  movl   %eax, -0x14(%ebp)
0xb08ea:  calll  0x13f0e0                  ; symbol stub for: objc_retain
0xb08ef:  movl   -0xc(%ebp), %ecx
0xb08f2:  movl   %ecx, (%esp)
0xb08f5:  movl   %eax, -0x18(%ebp)
0xb08f8:  calll  0x13f0e0                  ; symbol stub for: objc_retain
0xb08fd:  movl   -0x8(%ebp), %ecx
0xb0900:  movl   %ecx, (%esp)
0xb0903:  movl   -0x10(%ebp), %edx
0xb0906:  movl   %edx, 0x4(%esp)
0xb090a:  movl   -0xc(%ebp), %esi
0xb090d:  movl   %esi, 0x8(%esp)
0xb0911:  movl   %eax, -0x1c(%ebp)
0xb0914:  calll  0xb0240                   ; there.ViewController.collectionView (there.ViewController)(ObjectiveC.UICollectionView, cellForItemAtIndexPath : ObjectiveC.NSIndexPath) -> ObjectiveC.UICollectionViewCell at ViewController.swift:124
0xb0919:  movl   %esp, %ecx
0xb091b:  movl   %eax, (%ecx)
0xb091d:  calll  0x13f06e                  ; symbol stub for: objc_autoreleaseReturnValue
0xb0922:  addl   $0x24, %esp
0xb0925:  popl   %esi
0xb0926:  popl   %ebp
0xb0927:  retl   

UIKit`-[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:]:
0x2730b98:  pushl  %ebp
0x2730b99:  movl   %esp, %ebp
0x2730b9b:  pushl  %ebx
0x2730b9c:  pushl  %edi
0x2730b9d:  pushl  %esi
0x2730b9e:  subl   $0x5c, %esp
0x2730ba1:  calll  0x2730ba6                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 14
0x2730ba6:  popl   %esi
0x2730ba7:  movl   0x8(%ebp), %edi
0x2730baa:  movl   0x6307aa(%esi), %ebx
0x2730bb0:  cmpl   $0x0, (%edi,%ebx)
0x2730bb4:  jne    0x2730c29                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 145
0x2730bb6:  movl   0x6276ba(%esi), %eax
0x2730bbc:  movl   0x611b46(%esi), %ecx
0x2730bc2:  movl   %ecx, 0x4(%esp)
0x2730bc6:  movl   %eax, (%esp)
0x2730bc9:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730bce:  movl   %eax, -0x34(%ebp)
0x2730bd1:  movl   0x6276be(%esi), %eax
0x2730bd7:  movl   0x611b4a(%esi), %ecx
0x2730bdd:  leal   0x31216a(%esi), %edx
0x2730be3:  movl   %edx, 0x8(%esp)
0x2730be7:  movl   %ecx, 0x4(%esp)
0x2730beb:  movl   %eax, (%esp)
0x2730bee:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730bf3:  movl   0x611b4e(%esi), %ecx
0x2730bf9:  leal   0x519532(%esi), %edx
0x2730bff:  movl   %edx, 0x18(%esp)
0x2730c03:  movl   %eax, 0x10(%esp)
0x2730c07:  movl   %edi, 0xc(%esp)
0x2730c0b:  movl   0xc(%ebp), %eax
0x2730c0e:  movl   %eax, 0x8(%esp)
0x2730c12:  movl   %ecx, 0x4(%esp)
0x2730c16:  movl   -0x34(%ebp), %eax
0x2730c19:  movl   %eax, (%esp)
0x2730c1c:  movl   $0x51c, 0x14(%esp)
0x2730c24:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730c29:  movl   0x10(%ebp), %edx
0x2730c2c:  movl   0x63075a(%esi), %eax
0x2730c32:  movl   (%edi,%eax), %eax
0x2730c35:  testl  %eax, %eax
0x2730c37:  je     0x2730c7d                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 229
0x2730c39:  movl   0x6307b6(%esi), %ecx
0x2730c3f:  cmpl   $0x1, (%edi,%ecx)
0x2730c43:  jne    0x2730c7d                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 229
0x2730c45:  movl   0x611e16(%esi), %ecx
0x2730c4b:  movl   %edx, 0x8(%esp)
0x2730c4f:  movl   %ecx, 0x4(%esp)
0x2730c53:  movl   %eax, (%esp)
0x2730c56:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730c5b:  movl   0x10(%ebp), %edx
0x2730c5e:  testb  %al, %al
0x2730c60:  je     0x2730c7d                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 229
0x2730c62:  movl   0x630752(%esi), %eax
0x2730c68:  movl   (%edi,%eax), %eax
0x2730c6b:  movl   0x611a4e(%esi), %ecx
0x2730c71:  movl   %ecx, 0x4(%esp)
0x2730c75:  movl   %eax, (%esp)
0x2730c78:  jmp    0x273100d                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 1141
0x2730c7d:  movl   (%edi,%ebx), %eax
0x2730c80:  movl   0x62428a(%esi), %ecx
0x2730c86:  movl   %edx, 0xc(%esp)
0x2730c8a:  movl   %edi, 0x8(%esp)
0x2730c8e:  movl   %ecx, 0x4(%esp)
0x2730c92:  movl   %eax, (%esp)
0x2730c95:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730c9a:  movl   %eax, %ebx
0x2730c9c:  testl  %ebx, %ebx
0x2730c9e:  jne    0x2730d19                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 385
0x2730ca0:  movl   0x6276ba(%esi), %eax
0x2730ca6:  movl   0x611b46(%esi), %ecx
0x2730cac:  movl   %ecx, 0x4(%esp)
0x2730cb0:  movl   %eax, (%esp)
0x2730cb3:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730cb8:  movl   %eax, %edi
0x2730cba:  movl   0x6276be(%esi), %eax
0x2730cc0:  movl   0x611b4a(%esi), %ecx
0x2730cc6:  leal   0x31216a(%esi), %edx
0x2730ccc:  movl   %edx, 0x8(%esp)
0x2730cd0:  movl   %ecx, 0x4(%esp)
0x2730cd4:  movl   %eax, (%esp)
0x2730cd7:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730cdc:  movl   0x611b4e(%esi), %ecx
0x2730ce2:  movl   0x10(%ebp), %edx
0x2730ce5:  movl   %edx, 0x1c(%esp)
0x2730ce9:  leal   0x519542(%esi), %edx
0x2730cef:  movl   %edx, 0x18(%esp)
0x2730cf3:  movl   %eax, 0x10(%esp)
0x2730cf7:  movl   0x8(%ebp), %eax
0x2730cfa:  movl   %eax, 0xc(%esp)
0x2730cfe:  movl   0xc(%ebp), %eax
0x2730d01:  movl   %eax, 0x8(%esp)
0x2730d05:  movl   %ecx, 0x4(%esp)
0x2730d09:  movl   %edi, (%esp)
0x2730d0c:  movl   $0x522, 0x14(%esp)
0x2730d14:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730d19:  movl   0x6154de(%esi), %eax
0x2730d1f:  movl   %eax, 0x4(%esp)
0x2730d23:  movl   %ebx, (%esp)
0x2730d26:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730d2b:  testl  %eax, %eax
0x2730d2d:  jne    0x2730da1                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 521
0x2730d2f:  movl   0x6276ba(%esi), %eax
0x2730d35:  movl   0x611b46(%esi), %ecx
0x2730d3b:  movl   %ecx, 0x4(%esp)
0x2730d3f:  movl   %eax, (%esp)
0x2730d42:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730d47:  movl   %eax, %edi
0x2730d49:  movl   0x6276be(%esi), %eax
0x2730d4f:  movl   0x611b4a(%esi), %ecx
0x2730d55:  leal   0x31216a(%esi), %edx
0x2730d5b:  movl   %edx, 0x8(%esp)
0x2730d5f:  movl   %ecx, 0x4(%esp)
0x2730d63:  movl   %eax, (%esp)
0x2730d66:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730d6b:  movl   0x611b4e(%esi), %ecx
0x2730d71:  leal   0x519552(%esi), %edx
0x2730d77:  movl   %edx, 0x18(%esp)
0x2730d7b:  movl   %eax, 0x10(%esp)
0x2730d7f:  movl   0x8(%ebp), %eax
0x2730d82:  movl   %eax, 0xc(%esp)
0x2730d86:  movl   0xc(%ebp), %eax
0x2730d89:  movl   %eax, 0x8(%esp)
0x2730d8d:  movl   %ecx, 0x4(%esp)
0x2730d91:  movl   %edi, (%esp)
0x2730d94:  movl   $0x523, 0x14(%esp)
0x2730d9c:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730da1:  movl   %ebx, %edi
0x2730da3:  movl   0x4d2486(%esi), %eax
0x2730da9:  movl   (%eax), %eax
0x2730dab:  testl  %eax, %eax
0x2730dad:  je     0x273101a                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 1154
0x2730db3:  cmpl   $0x6ffff, %eax
0x2730db8:  seta   %bl
0x2730dbb:  movl   0x62428e(%esi), %eax
0x2730dc1:  movl   %eax, 0x4(%esp)
0x2730dc5:  movl   %edi, (%esp)
0x2730dc8:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730dcd:  testb  %bl, %bl
0x2730dcf:  je     0x2730e64                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 716
0x2730dd5:  testb  %al, %al
0x2730dd7:  movl   %edi, %ebx
0x2730dd9:  movl   0x14(%ebp), %ecx
0x2730ddc:  jne    0x2730e8a                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 754
0x2730de2:  movl   0x6276ba(%esi), %eax
0x2730de8:  movl   0x611b46(%esi), %ecx
0x2730dee:  movl   %ecx, 0x4(%esp)
0x2730df2:  movl   %eax, (%esp)
0x2730df5:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730dfa:  movl   %eax, %edi
0x2730dfc:  movl   0x6276be(%esi), %eax
0x2730e02:  movl   0x611b4a(%esi), %ecx
0x2730e08:  leal   0x31216a(%esi), %edx
0x2730e0e:  movl   %edx, 0x8(%esp)
0x2730e12:  movl   %ecx, 0x4(%esp)
0x2730e16:  movl   %eax, (%esp)
0x2730e19:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730e1e:  movl   0x611b4e(%esi), %ecx
0x2730e24:  movl   %ebx, 0x20(%esp)
0x2730e28:  movl   0x10(%ebp), %edx
0x2730e2b:  movl   %edx, 0x1c(%esp)
0x2730e2f:  leal   0x519562(%esi), %edx
0x2730e35:  movl   %edx, 0x18(%esp)
0x2730e39:  movl   %eax, 0x10(%esp)
0x2730e3d:  movl   0x8(%ebp), %eax
0x2730e40:  movl   %eax, 0xc(%esp)
0x2730e44:  movl   0xc(%ebp), %eax
0x2730e47:  movl   %eax, 0x8(%esp)
0x2730e4b:  movl   %ecx, 0x4(%esp)
0x2730e4f:  movl   %edi, (%esp)
0x2730e52:  movl   $0x524, 0x14(%esp)
0x2730e5a:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730e5f:  movl   0x14(%ebp), %ecx
0x2730e62:  jmp    0x2730e8a                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 754
0x2730e64:  testb  %al, %al
0x2730e66:  movl   %edi, %ebx
0x2730e68:  movl   0x14(%ebp), %ecx
0x2730e6b:  jne    0x2730e8a                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 754
0x2730e6d:  movl   %ebx, 0x8(%esp)
0x2730e71:  movl   0x10(%ebp), %eax
0x2730e74:  movl   %eax, 0x4(%esp)
0x2730e78:  leal   0x519562(%esi), %eax
0x2730e7e:  movl   %eax, (%esp)
0x2730e81:  movl   %ecx, %edi
0x2730e83:  calll  0x29148fa                 ; symbol stub for: NSLog
0x2730e88:  movl   %edi, %ecx
0x2730e8a:  movl   %ebx, -0x34(%ebp)
0x2730e8d:  movl   0x624292(%esi), %eax
0x2730e93:  movl   %ecx, 0x8(%esp)
0x2730e97:  movl   %eax, 0x4(%esp)
0x2730e9b:  movl   %ebx, (%esp)
0x2730e9e:  movl   %ecx, %edi
0x2730ea0:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730ea5:  movl   %eax, %ebx
0x2730ea7:  movl   0x611e16(%esi), %eax
0x2730ead:  movl   %edi, 0x8(%esp)
0x2730eb1:  movl   %eax, 0x4(%esp)
0x2730eb5:  movl   %ebx, (%esp)
0x2730eb8:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730ebd:  testb  %al, %al
0x2730ebf:  jne    0x2730f29                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 913
0x2730ec1:  movl   0x63072e(%esi), %ecx
0x2730ec7:  movl   %ecx, -0x38(%ebp)
0x2730eca:  movl   0x8(%ebp), %eax
0x2730ecd:  movl   (%eax,%ecx), %eax
0x2730ed0:  movl   0x61dfba(%esi), %ecx
0x2730ed6:  movl   %edi, 0xc(%esp)
0x2730eda:  movl   %ebx, 0x8(%esp)
0x2730ede:  movl   %ecx, 0x4(%esp)
0x2730ee2:  movl   %eax, (%esp)
0x2730ee5:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730eea:  testb  %al, %al
0x2730eec:  je     0x2730f29                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 913
0x2730eee:  movl   0x8(%ebp), %eax
0x2730ef1:  movl   -0x38(%ebp), %ecx
0x2730ef4:  movl   (%eax,%ecx), %ecx
0x2730ef7:  movl   0x61e006(%esi), %eax
0x2730efd:  movl   %edi, 0xc(%esp)
0x2730f01:  movl   %ebx, 0x8(%esp)
0x2730f05:  movl   %eax, 0x4(%esp)
0x2730f09:  movl   %ecx, (%esp)
0x2730f0c:  movl   %ecx, %ebx
0x2730f0e:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730f13:  movl   0x61dfe2(%esi), %ecx
0x2730f19:  movl   %eax, 0x8(%esp)
0x2730f1d:  movl   %ecx, 0x4(%esp)
0x2730f21:  movl   %ebx, (%esp)
0x2730f24:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730f29:  movl   %edi, %edx
0x2730f2b:  cmpb   $0x0, 0x18(%ebp)
0x2730f2f:  movl   0x8(%ebp), %edi
0x2730f32:  movl   -0x34(%ebp), %ebx
0x2730f35:  je     0x2730f88                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 1008
0x2730f37:  movl   0x6276d2(%esi), %eax
0x2730f3d:  movl   0x4d246e(%esi), %ecx
0x2730f43:  movl   %ecx, -0x30(%ebp)
0x2730f46:  movl   $0xc2000000, -0x2c(%ebp)
0x2730f4d:  movl   $0x0, -0x28(%ebp)
0x2730f54:  leal   0x487(%esi), %ecx
0x2730f5a:  movl   %ecx, -0x24(%ebp)
0x2730f5d:  leal   0x4f864a(%esi), %ecx
0x2730f63:  movl   %ecx, -0x20(%ebp)
0x2730f66:  movl   %edi, -0x1c(%ebp)
0x2730f69:  movl   %edx, -0x18(%ebp)
0x2730f6c:  movl   %ebx, -0x14(%ebp)
0x2730f6f:  movl   0x612d42(%esi), %ecx
0x2730f75:  leal   -0x30(%ebp), %edx
0x2730f78:  movl   %edx, 0x8(%esp)
0x2730f7c:  movl   %ecx, 0x4(%esp)
0x2730f80:  movl   %eax, (%esp)
0x2730f83:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730f88:  movl   0x62424a(%esi), %eax
0x2730f8e:  movl   %eax, 0x4(%esp)
0x2730f92:  movl   %ebx, (%esp)
0x2730f95:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730f9a:  movl   0x624272(%esi), %ecx
0x2730fa0:  movl   %ecx, 0x4(%esp)
0x2730fa4:  movl   %eax, (%esp)
0x2730fa7:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730fac:  movl   0x62429a(%esi), %ecx
0x2730fb2:  movl   %eax, 0xc(%esp)
0x2730fb6:  movl   %ebx, 0x8(%esp)
0x2730fba:  movl   %ecx, 0x4(%esp)
0x2730fbe:  movl   %edi, (%esp)
0x2730fc1:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2730fc6:  movl   0x630732(%esi), %eax
0x2730fcc:  movl   (%edi,%eax), %eax
0x2730fcf:  testb  $0x1, %ah
0x2730fd2:  je     0x2731000                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 1128
0x2730fd4:  movl   0x4d277e(%esi), %eax
0x2730fda:  movl   (%eax), %eax
0x2730fdc:  movl   (%edi,%eax), %eax
0x2730fdf:  movl   0x6241ee(%esi), %ecx
0x2730fe5:  movl   0x10(%ebp), %edx
0x2730fe8:  movl   %edx, 0x10(%esp)
0x2730fec:  movl   %ebx, 0xc(%esp)
0x2730ff0:  movl   %edi, 0x8(%esp)
0x2730ff4:  movl   %ecx, 0x4(%esp)
0x2730ff8:  movl   %eax, (%esp)
0x2730ffb:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2731000:  movl   0x611a4e(%esi), %eax
0x2731006:  movl   %eax, 0x4(%esp)
0x273100a:  movl   %ebx, (%esp)
0x273100d:  calll  0x2914ab6                 ; symbol stub for: objc_msgSend
0x2731012:  addl   $0x5c, %esp
0x2731015:  popl   %esi
0x2731016:  popl   %edi
0x2731017:  popl   %ebx
0x2731018:  popl   %ebp
0x2731019:  retl   
0x273101a:  movl   $0x70000, (%esp)
0x2731021:  calll  0x2017c4b                 ; _UIApplicationLinkedOnOrAfter
0x2731026:  movb   %al, %bl
0x2731028:  jmp    0x2730dbb                 ; -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 547

Answer 1

在代码中加入一些断点。逐步执行每个函数并查看变量包含的值。找不到它的nil变量。

如果错误实际出现在您提供的代码中，则错误可能出现在cell.askingUsernameLabel.text = arr[indexPath.row]行或self.collectionView.registerClass(CollectionViewCell.self, forCellWithReuseIdentifier:"CollectionViewCell")行。

你知道怎么放入异常断点吗？以下是：

enter image description here

swift - UICollectionView问题“致命错误：在展开Optional值时意外发现nil”

1 个答案: