Question

我试图在我的单元格中为UITableView创建一个按钮。我用了这段代码

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    tableView.dataSource = self

    let currentLastItem = food[indexPath.row]

    let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath) as UITableViewCell

    let btn = UIButton(type: UIButtonType.custom) as UIButton
    btn.backgroundColor = UIColor.red
    btn.setTitle(currentLastItem.name as String, for: UIControlState.normal)
    btn.frame = CGRect(x: 15, y: 0, width: 300, height: 30)
    btn.addTarget(self, action: Selector(("buttonPressed:")), for: UIControlEvents.touchUpInside)
    btn.tag = indexPath.row
    cell.contentView.addSubview(btn)

    return cell
}

@objc func buttonPressed(sender:UIButton!)
    {
        let buttonRow = sender.tag
        print("button is Pressed")
        print("Clicked Button Row is" ,buttonRow)
    }

当我编译它，或者当我进入表的视图时，它并没有给我一个错误，只是在我单击它时。

这是错误：

    2019-03-14 22:52:18.239124+0800 QRCodeReader[1635:35763] libMobileGestalt MobileGestalt.c:890: MGIsDeviceOneOfType is not supported on this platform.
2019-03-14 22:53:40.452471+0800 QRCodeReader[1635:35763] -[QRCodeReader.FoodsViewController buttonPressed:]: unrecognized selector sent to instance 0x7fa2f8636ae0
2019-03-14 22:53:40.463165+0800 QRCodeReader[1635:35763] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[QRCodeReader.FoodsViewController buttonPressed:]: unrecognized selector sent to instance 0x7fa2f8636ae0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010e35f1bb __exceptionPreprocess + 331
    1   libobjc.A.dylib                     0x000000010c336735 objc_exception_throw + 48
    2   CoreFoundation                      0x000000010e37df44 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   UIKitCore                           0x0000000117dbeb4a -[UIResponder doesNotRecognizeSelector:] + 287
    4   CoreFoundation                      0x000000010e363ed6 ___forwarding___ + 1446
    5   CoreFoundation                      0x000000010e365da8 _CF_forwarding_prep_0 + 120
    6   UIKitCore                           0x0000000117d91ecb -[UIApplication sendAction:to:from:forEvent:] + 83
    7   UIKitCore                           0x00000001177cd0bd -[UIControl sendAction:to:forEvent:] + 67
    8   UIKitCore                           0x00000001177cd3da -[UIControl _sendActionsForEvents:withEvent:] + 450
    9   UIKitCore                           0x00000001177cc31e -[UIControl touchesEnded:withEvent:] + 583
    10  UIKitCore                           0x0000000117965018 _UIGestureEnvironmentSortAndSendDelayedTouches + 5387
    11  UIKitCore                           0x000000011795efd1 _UIGestureEnvironmentUpdate + 1506
    12  UIKitCore                           0x000000011795e9ad -[UIGestureEnvironment _deliverEvent:toGestureRecognizers:usingBlock:] + 478
    13  UIKitCore                           0x000000011795e71d -[UIGestureEnvironment _updateForEvent:window:] + 200
    14  UIKitCore                           0x0000000117dce78a -[UIWindow sendEvent:] + 4058
    15  UIKitCore                           0x0000000117dac394 -[UIApplication sendEvent:] + 352
    16  UIKitCore                           0x0000000117e815a9 __dispatchPreprocessedEventFromEventQueue + 3054
    17  UIKitCore                           0x0000000117e841cb __handleEventQueueInternal + 5948
    18  CoreFoundation                      0x000000010e2c4721 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    19  CoreFoundation                      0x000000010e2c3f93 __CFRunLoopDoSources0 + 243
    20  CoreFoundation                      0x000000010e2be63f __CFRunLoopRun + 1263
    21  CoreFoundation                      0x000000010e2bde11 CFRunLoopRunSpecific + 625
    22  GraphicsServices                    0x0000000112b441dd GSEventRunModal + 62
    23  UIKitCore                           0x0000000117d9081d UIApplicationMain + 140
    24  QRCodeReader                        0x000000010b9e25c4 main + 68
    25  libdyld.dylib                       0x000000010f75c575 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

顺便说一句，lldb到底是什么？

Answer 1

选择器

只需将Selector(("buttonPressed:"))更改为#selector(buttonPressed)。确保选择器存在在您所在的类中（但您可以委托等），并且Xcode应该为您自动完成选择器。

LLDB

此外， LLDB 代表 L ow L evel D e b ugg。从this website中了解更多内容，并从this Medium article中了解如何使用它。

Answer 2

显然您是在以错误的方式调用选择器，只需使用以下代码即可：

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    tableView.dataSource = self

    let currentLastItem = food[indexPath.row]

    let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath) as UITableViewCell

    let btn = UIButton(type: UIButtonType.custom) as UIButton
    btn.backgroundColor = UIColor.red
    btn.setTitle(currentLastItem.name as String, for: UIControlState.normal)
    btn.frame = CGRect(x: 15, y: 0, width: 300, height: 30)
    btn.addTarget(self, action: #selector(buttonPressed(_:), for: UIControlEvents.touchUpInside)
    btn.tag = indexPath.row
    cell.contentView.addSubview(btn)

    return cell
}

@objc func buttonPressed(sender : UIButton )
    {
        let buttonRow = sender.tag
        print("button is Pressed")
        print("Clicked Button Row is: \(buttonRow)")
    }

无法识别的选择器已发送到实例0x7fa2f8636ae0

2 个答案:

选择器

LLDB