Search code examples
iosswiftswift3foundation

Declare "NSMapTable StrongObject" in Swift 3

How can I declare an NSMapTable in Swift 3? Why doesn't this example from Apple work?

let activeLines = NSMapTable.strongToStrongObjectsMapTable()

Xcode suggested change to:

let activeLines = NSMapTable.strongToStrongObjects()

but it still does not work.

I need convert this example to Swift 3

https://developer.apple.com/library/content/samplecode/TouchCanvas/Listings/TouchCanvas_CanvasView_swift.html

Solution

  • NSMapTable.strongToStrongObjects() will fail with the error:

    error: generic parameter 'KeyType' could not be inferred
NSMapTable.strongToStrongObjects()
           ^

    The class declaration of NSMapTable is:

    open class NSMapTable<KeyType : AnyObject, ObjectType : AnyObject> : NSObject, NSCopying, NSCoding, NSFastEnumeration

    You need to specify the key and object types of your map table in its declaration:

    NSMapTable<NSObject, NSObject>.strongToStrongObjects()