ios - Swift: Returning a recursive function (currying) -


i wanting return function in turn call itself. possible through returning closure calling itself?

my problem i'm unsure of correct syntax use here, i'm not sure if possible due having cyclic reference (and swift being heavy on compiler type checking)

i currying functions models , presenters not need know datagateway further decoupling code

some background information problem, api expects page number passed itself, not want store state. want function pass model can call next function when needs to.

i know curried function definition looks this:

function    (completion: ([example.product], uint) -> void) -> example.task?

look __function_defined_here__ in code samples

original - example code

func fetch(datagateway: datagateway, category: string)(page: uint)(completion: [product] -> void) -> task? {    return datagateway.productmap(category, page: page) { products in     completion(products.map { $0.build })   }  }

idea 1 - return tuple

func fetch(datagateway: datagateway, category: string)(page: uint)(completion: [product] -> void) -> (task?, __function_defined_here__) {    return (datagateway.productmap(category, page: page) { products in     completion(products.map { $0.build })   }, fetch(datagateway, category: category)(page: page + 1))  }

idea 2 - pass in completion

func fetch(datagateway: datagateway, category: string)(page: uint)(completion: ([product], __function_defined_here__) -> void) -> task? {    return datagateway.productmap(category, page: page) { products in     completion(products.map { $0.build }, fetch(datagateway, category: category)(page: page + 1))   }  }

i ended solving following, create class reference store next function in. pass reference object in completion of asynchronous operation. 

extension product {   class next {      typealias functiontype = (([product], next) -> void) -> task?     let fetch: functiontype      init(_ fetch: functiontype) {       self.fetch = fetch     }    }    func fetch(datagateway: datagateway, incategory category: string)(page: uint)(completion: ([product], next) -> void) -> task? {      return datagateway.products(incategory: category, page: page)() { products in       completion(products.map { $0.build }, next(fetch(datagateway, incategory: category)(page: page + 1)))     }    } }   let initial = product.fetch(datagateway, incategory: "1")(page: 0)

pass function in data model

data() { [weak self] products, next in    self?.data = products   self?.setneedsupdate()   self?.next = next }

scrolling down bottom of table view triggers above again, using next function instead of data


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