ios - 单击按钮时将按钮图像从一个图像更改为另一个图像时出错

Question

这是我的代码:

@IBAction func moreClicked(_ sender: UIButton) {
    if sender.currentImage == #imageLiteral(resourceName: "more_off"){
        sender.setImage(#imageLiteral(resourceName: "more_on"), for: .normal)
    }
    else
    {
        sender.setImage(#imageLiteral(resourceName: "more_off"), for: .normal)
    }

}

我收到此错误:

2018-09-05 11:03:28.708661+0530 musicPlayer[25450:590989] -[musicPlayer.SecondViewController more:]: unrecognized selector sent to instance 0x7fc1d4606d00

2018-09-05 11:03:28.715659+0530 musicPlayer[25450:590989] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[musicPlayer.SecondViewController more:]: unrecognized selector sent to instance 0x7fc1d4606d00' * First throw call stack: ( 0 CoreFoundation 0x00000001087ea1e6 exceptionPreprocess + 294 1 libobjc.A.dylib
0x0000000107a36031 objc_exception_throw + 48 2 CoreFoundation
0x000000010886b784 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132 3 UIKit 0x0000000108e956db -[UIResponder doesNotRecognizeSelector:] + 295 4 CoreFoundation 0x000000010876c898 ___forwarding_ + 1432 5 CoreFoundation
0x000000010876c278 _CF_forwarding_prep_0 + 120 6 UIKit
0x0000000108c683e8 -[UIApplication sendAction:to:from:forEvent:] + 83 7 UIKit 0x0000000108de37a4 -[UIControl sendAction:to:forEvent:] + 67 8 UIKit 0x0000000108de3ac1 -[UIControl _sendActionsForEvents:withEvent:] + 450 9 UIKit 0x0000000108de2a09 -[UIControl touchesEnded:withEvent:] + 580 10 UIKit 0x0000000108cdd0bf -[UIWindow _sendTouchesForEvent:] + 2729 11 UIKit 0x0000000108cde7c1 -[UIWindow sendEvent:] + 4086 12 UIKit
0x0000000108c82310 -[UIApplication sendEvent:] + 352 13 UIKit
0x00000001095c36af dispatchPreprocessedEventFromEventQueue + 2796 14 UIKit 0x00000001095c62c4 __handleEventQueueInternal + 5949 15 CoreFoundation 0x000000010878cbb1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17 16 CoreFoundation 0x00000001087714af __CFRunLoopDoSources0 + 271 17 CoreFoundation 0x0000000108770a6f __CFRunLoopRun + 1263 18 CoreFoundation
0x000000010877030b CFRunLoopRunSpecific + 635 19 GraphicsServices
0x000000010ff76a73 GSEventRunModal + 62 20 UIKit
0x0000000108c67057 UIApplicationMain + 159 21 musicPlayer
0x000000010711cc27 main + 55 22 libdyld.dylib
0x000000010cd4f955 start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

2018-09-05 11:03:28.708661+0530 musicPlayer[25450:590989] -[musicPlayer.SecondViewController more:]: unrecognized selector sent to instance 0x7fc1d4606d00

上面的消息意味着 SecondViewController 期望有一个名为 more: 的方法，但是当触发该操作并且此类的实例尝试查找 more: 时: 方法，它无法识别该方法并且应用程序崩溃。

我认为这里发生的事情是:您已将操作从 Xib/Storyboard 拖动到 VC 类并将其命名为 more:。之后，您将其手动重命名(不是“重构”>“重命名”)为 moreClicked:。这样，SecondViewController 的 IBAction 仍然指向名为 more: 的方法，但是您的类不再具有此类方法。

所以基本上，您需要从 xib/storyboard 中删除 IBAction 的现有引用，并使用新方法重新连接它:moreClicked:，一切都应该正常工作。