A helper to weakly capture an object in a block

Weak.swift

func weak<Object: AnyObject>(_ object: Object, block: @escaping (Object) -> Void) -> () -> Void {
    return { [weak object] in
        guard let object = object else { return }
        block(object)
    }
}

func weak<Object: AnyObject, Input>(_ object: Object, block: @escaping (Object, Input) -> Void) -> (Input) -> Void {
    return { [weak object] in
        guard let object = object else { return }
        block(object, $0)
    }
}

func weak<Object: AnyObject, Input, Output>(_ object: Object, block: @escaping (Object, Input) -> Output) -> (Input) -> Output? {
    return { [weak object] in
        guard let object = object else { return nil }

        return block(object, $0)
    }
}

// Uses:
let blockBefore: () -> Void = { [weak self[ in 
  guard let self = self else { return }
  self.doSomething() 
}
let blockAfter: () -> Void = weak(self) { _self in _self.doSomething() }

let blockBefore: (Int) -> Void = { [weak self] number in 
  guard let self = self else { return }
  self.update(number)
}
let blockAfter: (Int) -> Void = weak(self) { _self, number in _self.update(number) }
                                 
let blockBefore: (Int) -> String? = { [weak self] number in 
  guard let self = self else { return nil }
  return self.string(from: number) 
}
let blockAfter: (Int) -> String? = weak(self) { _self, number in _self.string(from: number) }