swift函数返回一个数组

Question

Im learning Swift and I can understand how to create a simple function that takes in an Array and returns an Array. Heres my code:

 func myArrayFunc(inputArray:Array) -> Array{

 var newArray = inputArray

// do stuff with newArray

 return newArray
 }

The red error I get is: Reference to generic type 'Array" requires arguments in <>

Answer 1

In Swift Array is generic type, so you have to specify what type array contains. For example:

func myArrayFunc(inputArray:Array<Int>) -> Array<Int> {}

If you want your function to be generic then use:

func myArrayFunc<T>(inputArray:Array<T>) -> Array<T> {}

If you don't want to specify type or have generic function use Any type:

func myArrayFunc(inputArray:Array<Any>) -> Array<Any> {}

Answer 2

Depends on what is it exactly you want to do. If you want a specialized function that takes an array of a specific type MyType, then you could write something like:

func myArrayFunc(inputArray: [MyType]) -> [MyType] {
    // do something to inputArray, perhaps copy it?
}

If you want a generic array function, then you have to use generics. This would take an array of generic type T and return an array of generic type U:

func myGenericArrayFunc<T, U>(inputArray: [T]) -> [U] {

}

Answer 3

There is no such thing as an Array in Swift, but there are arrays of a certain type, so you should give the function a generic type, like in:

func myArrayFunc<T>(inputArray:Array<T>) -> Array<T>{  
   // do what you want with the array
}

and then call it by instantiating T to a specific type, and passing an array of such type.

Answer 4

thanks all (especially Kirsteins). So I've come up with this example that works well and looks logical:

func myArrayFunc(inputArray:Array<String>) -> Array<String>{

var newArray = inputArray

// do stuff with newArray

return newArray
}

Answer 5

This should do it:

func myArrayFunc<T>(inputArray:Array<T>) -> Array<T> {

  var newArray = inputArray

  // do stuff with newArray

  return newArray
}

You declare the generic type T , which is just a placeholder. Because it has no requirements T can be replaced by any type (when the function is called). So your function could be called like this:

myArrayFunc([1, 2, 3])

or this:

myArrayFunc(["a", "b", "c"])

The preferred syntax is generally [T] rather than Array<T> , though. (although both are correct)

func myArrayFunc<T>(inputArray: [T]) -> [T] {

  var newArray = inputArray

  // do stuff with newArray

  return newArray
}

Answer 6

Try this

var test = doArray([true,true,true])

test.count
func doArray(arr : [AnyObject]) -> [AnyObject] {

   var _arr = arr

return _arr
}