I have this code
func getMeGoodies<T>(String:goodieName, callback:(goodie:T) -> ()) {
var goodie:T = //get it from the jug
callback(goodie)
}
And somewhere I want to call this
self.getMeGoodies("chocolatechip", callback: { (goodie) -> () in
println("eat the \(goodie)")
})
I am getting an error at the string "chocolatechip" saying it can't convert (blah blah). I believe it is not able to figure it out what T
is because it works when I return the goodie
from the function and assign it to a variable when calling it (or simply do a casting)
var chocolateChip:Goodie = self.getMeGoodies("chocolatechip", callback: { (goodie) -> () in
println("eat the \(goodie)")
})
or
self.getMeGoodies("chocolatechip", callback: { (goodie) -> () in
println("eat the \(goodie)")
}) as Goodie
Is there any way I can let swift know what type it is without the sorta hacky way of doing it.
If you add a type annotation to the closure parameter then the compiler can infer the generic type T
:
self.getMeGoodies("chocolatechip", callback: { (goodie : Goodie) -> () in
println("eat the \(goodie)")
})
Another method is to pass the type as an argument to the method:
func getMeGoodies<T>(type : T.Type, goodieName : String, callback:(goodie:T) -> ()) {
var goodie:T = 0 //get it from the jug
callback(goodie: goodie)
}
self.getMeGoodies(Goodie.self, goodieName: "chocolatechip", callback: { (goodie) in
println("eat the \(goodie)")
})
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