无法使用类型为“NSKeyValueChangeKey”的索引下标“[NSObject：AnyObject]”类型的值

Question

我在使用此代码时收到此错误。

错误：无法下标类型为'[NSObject：AnyObject]'的值，其索引类型为'NSKeyValueChangeKey'

func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutableRawPointer) {
    if !didFindMyLocation {
        let myLocation: CLLocation = change[NSKeyValueChangeNewKey] as CLLocation
        viewMap.camera = GMSCameraPosition.camera(withTarget: myLocation.coordinate, zoom: 10.0)
        viewMap.settings.myLocationButton = true

        didFindMyLocation = true
    }
}

Answer 1

这是observeValue(forKeyPath:of:change:context:)（Swift 4）的正确签名：

func observeValue(forKeyPath keyPath: String?, 
                of object: Any?, 
           change: [NSKeyValueChangeKey : Any]?, 
          context: UnsafeMutableRawPointer?)

无论语言版本如何，您的关键是将change: [NSObject : AnyObject]更改为change: [NSKeyValueChangeKey : Any]?。