ios – 如何正确地将选择器作为参数传递给swift

最后说

我有一个包含B的实例的A类.在A类中,我将一个A作为选择器的函数传递给B的一个方法.B使用这个选择器注册通知.但是,当通知进入时,它无法运行选择器并显示“无法识别的选择器发送到实例”.如果我把所有我想在B班做的事情都移到A班,那就行了.不过,我希望他们分开,好像更有条理.我对Objective-C和Swift来说相当新鲜,所以在这种情况下,我不知道如何传递选择器作为参数.斯威夫特答案会很棒.

ViewController.swift

class ViewController: UIViewController {

    var sessionCtrl : GKSessionControllerH!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view,typically from a nib.

        sessionCtrl = GKSessionControllerH()

        //  register notifications
        registerNotification()
    }

    func registerNotification() {
        sessionCtrl.registerNotification(GKGesture.Up,gestureHandler: "gestureUpHandler")
    }

    func gestureUpHandler() {
        dispatch_async(dispatch_get_main_queue()) {
            self.slidesViewCtrl!.prevPage()
        }
    }
}

GKSessionControllerH.swift

class GKSessionControllerH: NSObject,WCSessionDelegate {

    func handleGestureContent(content : AnyObject?) {

        // retrieve gesture
        let gesture = GKGesture(rawValue: content as! String)!
        print("Handheld device receives \(gesture)")

        //  post notification
        let notificationName = "ReceiveGesture\(gesture.rawValue)"
        NSNotificationCenter.defaultCenter().postNotificationName(notificationName,object: nil)

    }

    func registerNotification(gesture : GKGesture,gestureHandler : Selector) {

        let notificationName = "ReceiveGesture\(gesture.rawValue)"
        NSNotificationCenter.defaultCenter().addobserver(self,selector: gestureHandler,name: notificationName,object: nil)

    }
}

调试信息

2015-07-08 17:26:26.534 Slider[4608:1719498] -[Slider.GKSessionControllerH gestureDownHandler]: unrecognized selector sent to instance 0x7f912857a420
2015-07-08 17:26:26.543 Slider[4608:1719498] *** Terminating app due to uncaught exception 'NSinvalidargumentexception',reason: '-[Slider.GKSessionControllerH gestureDownHandler]: unrecognized selector sent to instance 0x7f912857a420'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010430dca5 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x00000001060f1dcd objc_exception_throw + 48
    2   CoreFoundation                      0x0000000104315fcd -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
    3   CoreFoundation                      0x00000001042634ea ___forwarding___ + 970
    4   CoreFoundation                      0x0000000104263098 _CF_forwarding_prep_0 + 120
    5   CoreFoundation                      0x00000001042db09c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
    6   CoreFoundation                      0x00000001042daddb _CFXRegistrationPost + 427
    7   CoreFoundation                      0x00000001042dab42 ___CFXNotificationPost_block_invoke + 50
    8   CoreFoundation                      0x000000010431d432 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1618
    9   CoreFoundation                      0x00000001041d3538 _CFXNotificationPost + 632
    10  Foundation                          0x00000001048bb3c4 -[NSNotificationCenter postNotificationName:object:userInfo:] + 66
    11  Slider                              0x00000001040f4e0e _TFC6Slider20GKSessionControllerH20handleGestureContentfS0_FGSqPSs9AnyObject__T_ + 1086
    12  Slider                              0x00000001040f4689 _TFC6Slider20GKSessionControllerH7sessionfS0_FTCSo9WCSession17didReceiveMessageGVSs10DictionarysspSs9AnyObject___T_ + 825
    13  Slider                              0x00000001040f49b7 _TToFC6Slider20GKSessionControllerH7sessionfS0_FTCSo9WCSession17didReceiveMessageGVSs10DictionarysspSs9AnyObject___T_ + 119
    14  WatchConnectivity                   0x00000001060c18cd WatchConnectivity + 35021
    15  libdispatch.dylib                   0x0000000106ab2b11 _dispatch_call_block_and_release + 12
    16  libdispatch.dylib                   0x0000000106ad280d _dispatch_client_callout + 8
    17  libdispatch.dylib                   0x0000000106ab92ec _dispatch_queue_drain + 2200
    18  libdispatch.dylib                   0x0000000106ab88ed _dispatch_queue_invoke + 233
    19  libdispatch.dylib                   0x0000000106abae9b _dispatch_root_queue_drain + 1412
    20  libdispatch.dylib                   0x0000000106aba912 _dispatch_worker_thread3 + 111
    21  libsystem_pthread.dylib             0x0000000106e11637 _pthread_wqthread + 729
    22  libsystem_pthread.dylib             0x0000000106e0f40d start_wqthread + 13
)
libc++abi.dylib: terminating with uncaught exception of type NSException

解决方法

以下是您的控制台输出中的大线索：

-[Slider.GKSessionControllerH gestureDownHandler]: unrecognized selector sent to instance 0x7f912857a420

所以,问题是,而不是试图在您的ViewController上调用gestureDownHandler,GKSessionControllerH正在注册为通知的接收者.

我们需要传递选择器和对象来调用选择器.

func registerNotification(gesture: GKGesture,gestureHandler: AnyObject,selector: Selector) {
    let notificationName = "ReceiveGesture\(gesture.rawValue)"
    NSNotificationCenter.defaultCenter().addobserver(gestureHandler,object: nil)
}

而现在,要注册：

sessionCtrl.registerNotification(.Up,gestureHandler: self,selector: "gestureUpHandler")

或者,可以说更像Swift,我们可以采取更多的封闭式方法.

首先,让我们让GKSessionControllerH收到通知,我们会传递一个闭包,当收到通知时,它将跟踪调用.

在GKSessionControllerH中,

var gestureActions = [()->Void] // an array of void-void closures

func gestureHandler() {
    for action in gestureActions {
        action()
    }
}

func registerNotification(gesture: GKGesture,action:()->Void) {
    let notificationName = "ReceiveGesture\(gesture.rawValue)"
    NSNotificationCenter.defaultCenter().addobserver(self,selector: "gestureHandler",object: nil)
}

现在,我们通过一个闭包(可以是一个方法)：

在ViewController中：

func registerNotification() {
    sessionCtrl.registerNotification(.Up,action: gestureUpHandler)
}

现在显然,这将需要更多的逻辑来处理所有不同的手势类型,但它的要点在这里.

ios – 如何正确地将选择器作为参数传递给swift

解决方法

相关文章