Information About Using

Does this mean that an error occurred and it didn't work?

vara=3
letb = SKAction.moveByX(-100,y:0.0, duration:a)

This is the signature of Swift.
+moveByX:y:duration:

class func moveByX(_deltaX:CGFloat,
                 y deltaY —CGFloat,
          duration sec:NSTimeInterval) - >SKAction

The argument given to duration is of type NSTimeInterval, so declare the variable itself as NSTimeInterval or

vara:NSTimeInterval=3
letb = SKAction.moveByX(-100,y:0.0, duration:a)

Or you have to cast it and adjust the pattern.

vara=3//<- In this way a is Int type.
letb = SKAction.moveByX(-100, y: 0.0, duration: NSTimeInterval(a))

(NSTimeInterval is Double's typealias in Swift, so the above model name can be Double.)

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